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Miao SB, Xie XL, Yin YJ, Zhao LL, Zhang F, Shu YN, Chen R, Chen P, Dong LH, Lin YL, Lv P, Zhang DD, Nie X, Xue ZY, Han M. Accumulation of Smooth Muscle 22α Protein Accelerates Senescence of Vascular Smooth Muscle Cells via Stabilization of p53 In Vitro and In Vivo. Arterioscler Thromb Vasc Biol 2017; 37:1849-1859. [DOI: 10.1161/atvbaha.117.309378] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 08/01/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Sui-Bing Miao
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Xiao-Li Xie
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Ya-Juan Yin
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Li-Li Zhao
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Fan Zhang
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Ya-Nan Shu
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Rong Chen
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Peng Chen
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Li-Hua Dong
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Yan-Ling Lin
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Pin Lv
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Dan-Dan Zhang
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Xi Nie
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Zhen-Ying Xue
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
| | - Mei Han
- From the Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, and Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, P. R. China
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Actin Tyrosine-53-Phosphorylation in Neuronal Maturation and Synaptic Plasticity. J Neurosci 2017; 36:5299-313. [PMID: 27170127 DOI: 10.1523/jneurosci.2649-15.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 03/31/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Rapid reorganization and stabilization of the actin cytoskeleton in dendritic spines enables cellular processes underlying learning, such as long-term potentiation (LTP). Dendritic spines are enriched in exceptionally short and dynamic actin filaments, but the studies so far have not revealed the molecular mechanisms underlying the high actin dynamics in dendritic spines. Here, we show that actin in dendritic spines is dynamically phosphorylated at tyrosine-53 (Y53) in rat hippocampal and cortical neurons. Our findings show that actin phosphorylation increases the turnover rate of actin filaments and promotes the short-term dynamics of dendritic spines. During neuronal maturation, actin phosphorylation peaks at the first weeks of morphogenesis, when dendritic spines form, and the amount of Y53-phosphorylated actin decreases when spines mature and stabilize. Induction of LTP transiently increases the amount of phosphorylated actin and LTP induction is deficient in neurons expressing mutant actin that mimics phosphorylation. Actin phosphorylation provides a molecular mechanism to maintain the high actin dynamics in dendritic spines during neuronal development and to induce fast reorganization of the actin cytoskeleton in synaptic plasticity. In turn, dephosphorylation of actin is required for the stabilization of actin filaments that is necessary for proper dendritic spine maturation and LTP maintenance. SIGNIFICANCE STATEMENT Dendritic spines are small protrusions from neuronal dendrites where the postsynaptic components of most excitatory synapses reside. Precise control of dendritic spine morphology and density is critical for normal brain function. Accordingly, aberrant spine morphology is linked to many neurological diseases. The actin cytoskeleton is a structural element underlying the proper morphology of dendritic spines. Therefore, defects in the regulation of the actin cytoskeleton in neurons have been implicated in neurological diseases. Here, we revealed a novel mechanism for regulating neuronal actin cytoskeleton that explains the specific organization and dynamics of actin in spines. The better we understand the regulation of the dendritic spine morphology, the better we understand what goes wrong in neurological diseases.
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Fukujin F, Nakajima A, Shimada N, Sawai S. Self-organization of chemoattractant waves in Dictyostelium depends on F-actin and cell-substrate adhesion. J R Soc Interface 2016; 13:20160233. [PMID: 27358278 PMCID: PMC4938087 DOI: 10.1098/rsif.2016.0233] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/01/2016] [Indexed: 12/25/2022] Open
Abstract
In the social amoeba Dictyostelium discoideum, travelling waves of extracellular cyclic adenosine monophosphate (cAMP) self-organize in cell populations and direct aggregation of individual cells to form multicellular fruiting bodies. In contrast to the large body of studies that addressed how movement of cells is determined by spatial and temporal cues encoded in the dynamic cAMP gradients, how cell mechanics affect the formation of a self-generated chemoattractant field has received less attention. Here, we show, by live cell imaging analysis, that the periodicity of the synchronized cAMP waves increases in cells treated with the actin inhibitor latrunculin. Detail analysis of the extracellular cAMP-induced transients of cytosolic cAMP (cAMP relay response) in well-isolated cells demonstrated that their amplitude and duration were markedly reduced in latrunculin-treated cells. Similarly, in cells strongly adhered to a poly-l-lysine-coated surface, the response was suppressed, and the periodicity of the population-level oscillations was markedly lengthened. Our results suggest that cortical F-actin is dispensable for the basic low amplitude relay response but essential for its full amplification and that this enhanced response is necessary to establish high-frequency signalling centres. The observed F-actin dependence may prevent aggregation centres from establishing in microenvironments that are incompatible with cell migration.
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Affiliation(s)
- Fumihito Fukujin
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Akihiko Nakajima
- Research Center for Complex Systems Biology, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Nao Shimada
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Satoshi Sawai
- Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan Research Center for Complex Systems Biology, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan PRESTO, Japan Science and Technology Agency, Kawaguchi-shi, Saitama 332-0012, Japan
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von Bülow J, Golldack A, Albers T, Beitz E. The amoeboidalDictyosteliumaquaporin AqpB is gated via Tyr216 andaqpBgene deletion affects random cell motility. Biol Cell 2015; 107:78-88. [DOI: 10.1111/boc.201400070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 12/22/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Julia von Bülow
- Pharmaceutical and Medicinal Chemistry; Christian-Albrechts-University of Kiel; Kiel 24118 Germany
| | - André Golldack
- Pharmaceutical and Medicinal Chemistry; Christian-Albrechts-University of Kiel; Kiel 24118 Germany
| | - Tineke Albers
- Pharmaceutical and Medicinal Chemistry; Christian-Albrechts-University of Kiel; Kiel 24118 Germany
| | - Eric Beitz
- Pharmaceutical and Medicinal Chemistry; Christian-Albrechts-University of Kiel; Kiel 24118 Germany
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Cao X, Yan J, Shu S, Brzostowski JA, Jin T. Arrestins function in cAR1 GPCR-mediated signaling and cAR1 internalization in the development of Dictyostelium discoideum. Mol Biol Cell 2014; 25:3210-21. [PMID: 25143405 PMCID: PMC4196870 DOI: 10.1091/mbc.e14-03-0834] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Evolutionarily conserved arrestin-like proteins are key components of the cAR1-mediated ERK2 activation that controls cAMP cell–cell signaling during Dictyostelium aggregation. They are also involved in ligand-induced cAR1 internalization, which is required for the switch of cAMP receptors during multicellular development. Oscillation of chemical signals is a common biological phenomenon, but its regulation is poorly understood. At the aggregation stage of Dictyostelium discoideum development, the chemoattractant cAMP is synthesized and released at 6-min intervals, directing cell migration. Although the G protein–coupled cAMP receptor cAR1 and ERK2 are both implicated in regulating the oscillation, the signaling circuit remains unknown. Here we report that D. discoideum arrestins regulate the frequency of cAMP oscillation and may link cAR1 signaling to oscillatory ERK2 activity. Cells lacking arrestins (adcB−C−) display cAMP oscillations during the aggregation stage that are twice as frequent as for wild- type cells. The adcB−C− cells also have a shorter period of transient ERK2 activity and precociously reactivate ERK2 in response to cAMP stimulation. We show that arrestin domain–containing protein C (AdcC) associates with ERK2 and that activation of cAR1 promotes the transient membrane recruitment of AdcC and interaction with cAR1, indicating that arrestins function in cAR1-controlled periodic ERK2 activation and oscillatory cAMP signaling in the aggregation stage of D. discoideum development. In addition, ligand-induced cAR1 internalization is compromised in adcB−C− cells, suggesting that arrestins are involved in elimination of high-affinity cAR1 receptors from cell surface after the aggregation stage of multicellular development.
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Affiliation(s)
- Xiumei Cao
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jianshe Yan
- Shanghai Institute of Immunology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institutes of Health, Rockville, MD 20852
| | - Shi Shu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Joseph A Brzostowski
- Laboratory of Immunogenetics Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852
| | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institutes of Health, Rockville, MD 20852
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Moving towards a paradigm: common mechanisms of chemotactic signaling in Dictyostelium and mammalian leukocytes. Cell Mol Life Sci 2014; 71:3711-47. [PMID: 24846395 DOI: 10.1007/s00018-014-1638-8] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/24/2014] [Accepted: 04/29/2014] [Indexed: 12/31/2022]
Abstract
Chemotaxis, or directed migration of cells along a chemical gradient, is a highly coordinated process that involves gradient sensing, motility, and polarity. Most of our understanding of chemotaxis comes from studies of cells undergoing amoeboid-type migration, in particular the social amoeba Dictyostelium discoideum and leukocytes. In these amoeboid cells the molecular events leading to directed migration can be conceptually divided into four interacting networks: receptor/G protein, signal transduction, cytoskeleton, and polarity. The signal transduction network occupies a central position in this scheme as it receives direct input from the receptor/G protein network, as well as feedback from the cytoskeletal and polarity networks. Multiple overlapping modules within the signal transduction network transmit the signals to the actin cytoskeleton network leading to biased pseudopod protrusion in the direction of the gradient. The overall architecture of the networks, as well as the individual signaling modules, is remarkably conserved between Dictyostelium and mammalian leukocytes, and the similarities and differences between the two systems are the subject of this review.
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Liu X, Shu S, Yu S, Lee DY, Piszczek G, Gucek M, Wang G, Korn ED. Biochemical and biological properties of cortexillin III, a component of Dictyostelium DGAP1-cortexillin complexes. Mol Biol Cell 2014; 25:2026-38. [PMID: 24807902 PMCID: PMC4072576 DOI: 10.1091/mbc.e13-08-0457] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cortexillin III, a member of the α-actinin/spectrin subfamily of Dictyostelium calponin homology proteins, forms heterodimers with cortexillins I and II that bind to the GAP protein DGAP1 in vivo. Cortexillin III complexes may be negative regulators of cell growth, pinocytosis, and phagocytosis, as all are enhanced in cortexillin III–null cells. Cortexillins I–III are members of the α-actinin/spectrin subfamily of Dictyostelium calponin homology proteins. Unlike recombinant cortexillins I and II, which form homodimers as well as heterodimers in vitro, we find that recombinant cortexillin III is an unstable monomer but forms more stable heterodimers when coexpressed in Escherichia coli with cortexillin I or II. Expressed cortexillin III also forms heterodimers with both cortexillin I and II in vivo, and the heterodimers complex in vivo with DGAP1, a Dictyostelium GAP protein. Binding of cortexillin III to DGAP1 requires the presence of either cortexillin I or II; that is, cortexillin III binds to DGAP1 only as a heterodimer, and the heterodimers form in vivo in the absence of DGAP1. Expressed cortexillin III colocalizes with cortexillins I and II in the cortex of vegetative amoebae, the leading edge of motile cells, and the cleavage furrow of dividing cells. Colocalization of cortexillin III and F-actin may require the heterodimer/DGAP1 complex. Functionally, cortexillin III may be a negative regulator of cell growth, cytokinesis, pinocytosis, and phagocytosis, as all are enhanced in cortexillin III–null cells.
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Affiliation(s)
- Xiong Liu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Shi Shu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Shuhua Yu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Duck-Yeon Lee
- Biochemistry Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Grzegorz Piszczek
- Biophysics Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Marjan Gucek
- Proteomics Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Guanghui Wang
- Proteomics Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Edward D Korn
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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Choi CH, Thomason PA, Zaki M, Insall RH, Barber DL. Phosphorylation of actin-related protein 2 (Arp2) is required for normal development and cAMP chemotaxis in Dictyostelium. J Biol Chem 2013; 288:2464-74. [PMID: 23223240 PMCID: PMC3554915 DOI: 10.1074/jbc.m112.435313] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 11/30/2012] [Indexed: 12/17/2022] Open
Abstract
Phosphorylation of the actin-related protein 2 (Arp2) subunit of the Arp2/3 complex on evolutionarily conserved threonine and tyrosine residues was recently identified and shown to be necessary for nucleating activity of the Arp2/3 complex and membrane protrusion of Drosophila cells. Here we use the Dictyostelium diploid system to replace the essential Arp2 protein with mutants that cannot be phosphorylated at Thr-235/6 and Tyr-200. We found that aggregation of the resulting mutant cells after starvation was substantially slowed with delayed early developmental gene expression and that chemotaxis toward a cAMP gradient was defective with loss of polarity and attenuated F-actin assembly. Chemotaxis toward cAMP was also diminished with reduced cell speed and directionality and shorter pseudopod lifetime when Arp2 phosphorylation mutant cells were allowed to develop longer to a responsive state similar to that of wild-type cells. However, clathrin-mediated endocytosis and chemotaxis under agar to folate in vegetative cells were only subtly affected in Arp2 phosphorylation mutants. Thus, phosphorylation of threonine and tyrosine is important for a subset of the functions of the Arp2/3 complex, in particular an unexpected major role in regulating development.
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Affiliation(s)
- Chang-Hoon Choi
- From the Department of Cell and Tissue Biology, University of California, San Francisco, California 94143 and
| | - Peter A. Thomason
- Cancer Research UK Beatson Institute for Cancer Research, Switchback Road, Glasgow G61 1BD, Scotland, United Kingdom
| | - Mehreen Zaki
- Cancer Research UK Beatson Institute for Cancer Research, Switchback Road, Glasgow G61 1BD, Scotland, United Kingdom
| | - Robert H. Insall
- Cancer Research UK Beatson Institute for Cancer Research, Switchback Road, Glasgow G61 1BD, Scotland, United Kingdom
| | - Diane L. Barber
- From the Department of Cell and Tissue Biology, University of California, San Francisco, California 94143 and
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A Gβγ effector, ElmoE, transduces GPCR signaling to the actin network during chemotaxis. Dev Cell 2012; 22:92-103. [PMID: 22264729 DOI: 10.1016/j.devcel.2011.11.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 10/19/2011] [Accepted: 11/15/2011] [Indexed: 10/14/2022]
Abstract
Activation of G protein-coupled receptors (GPCRs) leads to the dissociation of heterotrimeric G-proteins into Gα and Gβγ subunits, which go on to regulate various effectors involved in a panoply of cellular responses. During chemotaxis, Gβγ subunits regulate actin assembly and migration, but the protein(s) linking Gβγ to the actin cytoskeleton remains unknown. Here, we identified a Gβγ effector, ElmoE in Dictyostelium, and demonstrated that it is required for GPCR-mediated chemotaxis. Remarkably, ElmoE associates with Gβγ and Dock-like proteins to activate the small GTPase Rac, in a GPCR-dependent manner, and also associates with Arp2/3 complex and F-actin. Thus, ElmoE serves as a link between chemoattractant GPCRs, G-proteins and the actin cytoskeleton. The pathway, consisting of GPCR, Gβγ, Elmo/Dock, Rac, and Arp2/3, spatially guides the growth of dendritic actin networks in pseudopods of eukaryotic cells during chemotaxis.
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Araki T, Williams JG. Perturbations of the actin cytoskeleton activate a Dictyostelium STAT signalling pathway. Eur J Cell Biol 2012; 91:420-5. [PMID: 22365144 PMCID: PMC3315007 DOI: 10.1016/j.ejcb.2012.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/05/2012] [Accepted: 01/05/2012] [Indexed: 12/02/2022] Open
Abstract
The Dictyostelium transcription factor STATc is tyrosine phosphorylated and accumulates in the nucleus when cells are exposed either to hyper-osmotic stress or to the prestalk-inducing polyketide DIF-1. In the case of stress STAT activation is mediated by regulated dephosphorylation; whereby two serine residues on PTP3, the tyrosine phosphatase that de-activates STATc, become phosphorylated after exposure to stress so inhibiting enzymatic activity. We now show that the more highly regulated of the two PTP3 serine residues, S747, is also phosphorylated in response to DIF-1, suggesting a common activation mechanism. Hyper-osmotic stress causes a re-distribution of F-actin to the cortex, cell rounding and shrinkage and we show that DIF-1 induces a similar but transient F-actin re-distribution and rounding response. We also find that two mechanistically distinct inhibitors of actin polymerization, latrunculin A and cytochalasin A induce phosphorylation at S747 of PTP3 and activate STATc. We suggest that PTP3 phosphorylation, and consequent STATc activation, are regulated by changes in F-actin polymerization status during stress and DIF-induced cytoskeletal remodelling.
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Affiliation(s)
- Tsuyoshi Araki
- College of Life Sciences, Welcome Trust Biocentre, University of Dundee, Dow St., Dundee DD1 5EH, United Kingdom
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Sultana H, Neelakanta G, Rivero F, Blau-Wasser R, Schleicher M, Noegel AA. Ectopic expression of cyclase associated protein CAP restores the streaming and aggregation defects of adenylyl cyclase a deficient Dictyostelium discoideum cells. BMC DEVELOPMENTAL BIOLOGY 2012; 12:3. [PMID: 22239817 PMCID: PMC3316131 DOI: 10.1186/1471-213x-12-3] [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: 08/17/2011] [Accepted: 01/12/2012] [Indexed: 12/02/2022]
Abstract
Background Cell adhesion, an integral part of D. discoideum development, is important for morphogenesis and regulated gene expression in the multicellular context and is required to trigger cell-differentiation. G-protein linked adenylyl cyclase pathways are crucially involved and a mutant lacking the aggregation specific adenylyl cyclase ACA does not undergo multicellular development. Results Here, we have investigated the role of cyclase-associated protein (CAP), an important regulator of cell polarity and F-actin/G-actin ratio in the aca- mutant. We show that ectopic expression of GFP-CAP improves cell polarization, streaming and aggregation in aca- cells, but it fails to completely restore development. Our studies indicate a requirement of CAP in the ACA dependent signal transduction for progression of the development of unicellular amoebae into multicellular structures. The reduced expression of the cell adhesion molecule DdCAD1 together with csA is responsible for the defects in aca- cells to initiate multicellular development. Early development was restored by the expression of GFP-CAP that enhanced the DdCAD1 transcript levels and to a lesser extent the csA mRNA levels. Conclusions Collectively, our data shows a novel role of CAP in regulating cell adhesion mechanisms during development that might be envisioned to unravel the functions of mammalian CAP during animal embryogenesis.
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Affiliation(s)
- Hameeda Sultana
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Köln, Germany.
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Shu S, Liu X, Kriebel PW, Daniels MP, Korn ED. Actin cross-linking proteins cortexillin I and II are required for cAMP signaling during Dictyostelium chemotaxis and development. Mol Biol Cell 2011; 23:390-400. [PMID: 22114350 PMCID: PMC3258182 DOI: 10.1091/mbc.e11-09-0764] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Double deletion of actin-binding proteins cortexillin I and II alters the actin cytoskeleton (bundled actin filaments accumulate in the cell cortex) of Dictyostelium, substantially inhibits all molecular responses to extracellular cAMP, and completely blocks cell streaming and development of cells into mature fruiting bodies. Starvation induces Dictyostelium amoebae to secrete cAMP, toward which other amoebae stream, forming multicellular mounds that differentiate and develop into fruiting bodies containing spores. We find that the double deletion of cortexillin (ctx) I and II alters the actin cytoskeleton and substantially inhibits all molecular responses to extracellular cAMP. Synthesis of cAMP receptor and adenylyl cyclase A (ACA) is inhibited, and activation of ACA, RasC, and RasG, phosphorylation of extracellular signal regulated kinase 2, activation of TORC2, and stimulation of actin polymerization and myosin assembly are greatly reduced. As a consequence, cell streaming and development are completely blocked. Expression of ACA–yellow fluorescent protein in the ctxI/ctxII–null cells significantly rescues the wild-type phenotype, indicating that the primary chemotaxis and development defect is the inhibition of ACA synthesis and cAMP production. These results demonstrate the critical importance of a properly organized actin cytoskeleton for cAMP-signaling pathways, chemotaxis, and development in Dictyostelium.
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Affiliation(s)
- Shi Shu
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA
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Tyrosine phosphorylation of actin during microcyst formation and germination in Polysphondylium pallidum. Protist 2011; 162:490-502. [PMID: 21316301 DOI: 10.1016/j.protis.2010.11.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Accepted: 11/25/2010] [Indexed: 11/20/2022]
Abstract
High osmolarity causes amoebae of the cellular slime mould Polysphondylium pallidum to individually encyst, forming microcysts. During microcyst differentiation, actin is tyrosine phosphorylated. Tyrosine phosphorylation of actin is independent of encystment conditions and occurs during the final stages of microcyst formation. During microcyst germination, actin undergoes dephosphorylation prior to amoebal emergence. Renewed phosphorylation of actin in germinating microcysts can be triggered by increasing the osmolarity of the medium which inhibits emergence. Immunofluorescence reveals that actin is dispersed throughout the cytoplasm in dormant microcysts. Following the onset of germination, actin is observed around vesicles where it co-localizes with phosphotyrosine. Prior to emergence, actin localizes to patches near the cell surface. Increasing osmolarity disrupts this localization and causes actin to redistribute throughout the cytoplasm, a situation similar to that observed in dormant microcysts. The tyrosine phosphorylation state of actin does not appear to influence the long-term viability of dormant microcysts. Together, these results indicate an association between actin tyrosine phosphorylation, organization of the actin cytoskeleton, and microcyst dormancy.
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