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Moens PDJ, Bagatolli LA. Profilin binding to sub-micellar concentrations of phosphatidylinositol (4,5) bisphosphate and phosphatidylinositol (3,4,5) trisphosphate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1768:439-49. [PMID: 17275780 DOI: 10.1016/j.bbamem.2006.12.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 11/20/2006] [Accepted: 12/14/2006] [Indexed: 02/07/2023]
Abstract
Profilin is a small (12-15 kDa) actin binding protein which promotes filament turnover. Profilin is also involved in the signaling pathway linking receptors in the cell membrane to the microfilament system within the cell. Profilin is thought to play critical roles in this signaling pathway through its interaction with phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] (P.J. Lu, W.R. Shieh, S.G. Rhee, H.L. Yin, C.S. Chen, Lipid products of phosphoinositide 3-kinase bind human profilin with high affinity, Biochemistry 35 (1996) 14027-14034). To date, profilin's interaction with polyphosphoinositides (PPI) has only been studied in micelles or small vesicles. Profilin binds with high affinity to small clusters of PI(4,5)P(2) molecules. In this work, we investigated the interactions of profilin with sub-micellar concentrations of PI(4,5)P(2) and PI(3,4,5)P(3). Fluorescence anisotropy was used to determine the relevant dissociation constants for binding of sub-micellar concentrations of fluorescently labeled PPI lipids to profilin and we show that these are significantly different from those determined for profilin interaction with micelles or small vesicles. We also show that profilin binds more tightly to sub-micellar concentrations of PI(3,4,5)P(3) (K(D)=720 microM) than to sub-micellar concentrations of PI(4,5)P(2) (K(D)=985 microM). Despite the low affinity for sub-micellar concentration of PI(4,5)P(2), profilin was shown to bind to giant unilamellar vesicles in presence of 0.5% mole fraction of PI(4,5)P(2) The implications of these findings are discussed.
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Affiliation(s)
- Pierre D J Moens
- School of Biological, Biomedical and Molecular Sciences, The University of New England, Armidale, NSW 2351 Australia.
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Polet D, Lambrechts A, Vandepoele K, Vandekerckhove J, Ampe C. On the origin and evolution of vertebrate and viral profilins. FEBS Lett 2006; 581:211-7. [PMID: 17187785 DOI: 10.1016/j.febslet.2006.12.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 12/06/2006] [Indexed: 11/23/2022]
Abstract
The three dimensional structures of profilins from invertebrates and vertebrates are remarkably similar despite low sequence similarity. Their evolutionary relationship remains thus enigmatic. A phylogenetic analysis of profilins from Deuterostoma indicates that profilin III and IV isoforms each form distinct groups. Profilin IV is most related to invertebrate profilins and originated prior to vertebrate evolution whereas separation of profilin I, II and III isoforms occurred early in vertebrate evolution. Viral profilins are most similar to profilin III. In silico analysis of representative profilin gene structures corroborates the phylogenetic result and we discuss this in terms of biochemical differences.
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Affiliation(s)
- Debby Polet
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
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Ling K, Schill NJ, Wagoner MP, Sun Y, Anderson RA. Movin' on up: the role of PtdIns(4,5)P2 in cell migration. Trends Cell Biol 2006; 16:276-84. [PMID: 16616849 DOI: 10.1016/j.tcb.2006.03.007] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 02/17/2006] [Accepted: 03/23/2006] [Indexed: 11/28/2022]
Abstract
Cell migration requires the coordination of many biochemical events, including cell-matrix contact turnover and cytoskeletal restructuring. Recent advances further implicate phosphatidylinositol(4,5)-bisphosphate [PtdIns(4,5)P(2)] in the control of these events. Many proteins that are crucial to the assembly of the migration machinery are regulated by PtdIns(4,5)P(2). Coordinated synthesis of PtdIns(4,5)P(2) at these sites is dependent on the precise targeting of the type I phosphatidylinositol phosphate kinases (PIPKs). Two PIPKI isoforms target to, and generate, PtdIns(4,5)P(2) at membrane ruffles and focal adhesions during cell migration. Here, we discuss our current understanding of PtdIns(4,5)P(2) in the regulation of cell responses to migratory stimuli and how the migrating cell controls PtdIns(4,5)P(2) availability.
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Affiliation(s)
- Kun Ling
- Program in Molecular and Cellular Pharmacology, University of Wisconsin-Madison, Department of Pharmacology, University of Wisconsin Medical School, 1300 University Ave, Madison, WI 53706, USA
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Lambrechts A, Jonckheere V, Peleman C, Polet D, De Vos W, Vandekerckhove J, Ampe C. Profilin-I-ligand interactions influence various aspects of neuronal differentiation. J Cell Sci 2006; 119:1570-8. [PMID: 16569658 DOI: 10.1242/jcs.02884] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Differentiating neurons extend membrane protrusions that develop into growing neurites. The driving force for neurite outgrowth is the dynamic actin cytoskeleton, which is regulated by actin-binding proteins. In this study, we describe for the first time, the role of profilin I and its ligand interactions in neuritogenesis of PC12 cells. High-level overexpression of wild-type profilin I had an inhibitory effect on neurite outgrowth. Low levels of profilin I did not disturb this process, but these cells developed many more filopodia along the neurite shafts. Low-level overexpression of mutant forms of profilin I changed one or more aspects of PC12 differentiation. Expression of a profilin I mutant that is defective in actin binding (profilin I(R74E)) decreased neurite length and strongly inhibited filopodia formation. Cells expressing mutants defective in binding proline-rich ligands (profilin I(W3A) and profilin I(R136D)) differentiated faster, developed more and longer neurites and more branches. The profilin I(R136D) mutant, which is also defective in phosphatidylinositol 4,5-bisphosphate binding, enhanced neurite outgrowth even in the absence of NGF. Parental PC12 cells treated with the ROCK inhibitor Y27632, differentiate faster and display longer neurites and more branches. Similar effects were seen in cells expressing profilin I(WT), profilin I(W3A) and profilin I(R74E). By contrast, the profilin I(R136D)-expressing cells were insensitive to the ROCK inhibitor, suggesting that regulation of profilin I by phosphatidylinositol 4,5-bisphosphate metabolism is crucial for proper neurite outgrowth. Taken together, our data show the importance of the interaction of profilin I with actin, proline-rich proteins and phosphatidylinositol 4,5-bisphosphate in neuronal differentiation of PC12 cells.
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Affiliation(s)
- Anja Lambrechts
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Belgium.
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Polet D, Lambrechts A, Ono K, Mah A, Peelman F, Vandekerckhove J, Baillie DL, Ampe C, Ono S. Caenorhabditis elegans expresses three functional profilins in a tissue-specific manner. ACTA ACUST UNITED AC 2006; 63:14-28. [PMID: 16317718 PMCID: PMC2575421 DOI: 10.1002/cm.20102] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Profilins are actin binding proteins, which also interact with polyphosphoinositides and proline-rich ligands. On the basis of the genome sequence, three diverse profilin homologues (PFN) are predicted to exist in Caenorhabditis elegans. We show that all three isoforms PFN-1, PFN-2, and PFN-3 are expressed in vivo and biochemical studies indicate they bind actin and influence actin dynamics in a similar manner. In addition, they bind poly(L-proline) and phosphatidylinositol 4,5-bisphosphate micelles. PFN-1 is essential whereas PFN-2 and PFN-3 are nonessential. Immunostainings revealed different expression patterns for the profilin isoforms. In embryos, PFN-1 localizes in the cytoplasm and to the cell-cell contacts at the early stages, and in the nerve ring during later stages. During late embryogenesis, expression of PFN-3 was specifically detected in body wall muscle cells. In adult worms, PFN-1 is expressed in the neurons, the vulva, and the somatic gonad, PFN-2 in the intestinal wall, the spermatheca, and the pharynx, and PFN-3 localizes in a striking dot-like fashion in body wall muscle. Thus the model organism Caenorhabditis elegans expresses three profilin isoforms and is the first invertebrate animal with tissue-specific profilin expression.
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Affiliation(s)
- D. Polet
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- Department of Medical Protein Chemistry (VIB09), Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - A. Lambrechts
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- Department of Medical Protein Chemistry (VIB09), Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - K. Ono
- Department of Pathology, Emory University, Atlanta, Georgia
| | - A. Mah
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - F. Peelman
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- Department of Medical Protein Chemistry (VIB09), Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - J. Vandekerckhove
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- Department of Medical Protein Chemistry (VIB09), Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - D. L. Baillie
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | - C. Ampe
- Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- Department of Medical Protein Chemistry (VIB09), Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
- Correspondence to: C. Ampe, Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, A. Baertsoenkaai 3, B-9000 Ghent, Belgium. E-mail:
| | - S. Ono
- Department of Pathology, Emory University, Atlanta, Georgia
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Abstract
Phosphoinositide phosphates (PIPs) correspond to phosphorylated derivatives of phosphatidylinositol (PI). Despite their relatively low abundance in the plasma membrane, PIPs play a crucial role as precursors of second messengers and are themselves important signaling and targeting molecules. Indeed, modulation of levels of PIPs affects, for example, cortical actin organization, membrane dynamics, and cell migration. The focus of this review is on selected interesting targets of PIPs. Those proteins that bind PIPs and are involved in regulation of actin assembly, actin membrane linkage, and actin contractility are discussed, as well as those that are involved in signaling, such as small GTPases, protein kinases, and phosphatases, or in regulation of membrane dynamics.
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Affiliation(s)
- Verena Niggli
- Department of Pathology, University of Bern, CH-3010 Bern, Switzerland.
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Rommelaere H, Waterschoot D, Neirynck K, Vandekerckhove J, Ampe C. A method for rapidly screening functionality of actin mutants and tagged actins. Biol Proced Online 2004; 6:235-249. [PMID: 15514698 PMCID: PMC524212 DOI: 10.1251/bpo94] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Revised: 09/23/2004] [Accepted: 10/01/2004] [Indexed: 11/26/2022] Open
Abstract
Recombinant production and biochemical analysis of actin mutants has been hampered by the fact that actin has an absolute requirement for the eukaryotic chaperone CCT to reach its native state. We therefore have developed a method to rapidly screen the folding capacity and functionality of actin variants, by combining in vitro expression of labelled actin with analysis on native gels, band shift assays or copolymerization tests. Additionally, we monitor, using immuno-fluorescence, incorporation of actin variants in cytoskeletal structures in transfected cells. We illustrate the method by two examples. In one we show that tagged versions of actin do not always behave native-like and in the other we study some of the molecular defects of three beta-actin mutants that have been associated with diseases.
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Affiliation(s)
- Heidi Rommelaere
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Davy Waterschoot
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Katrien Neirynck
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Joël Vandekerckhove
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
| | - Christophe Ampe
- Flanders Interuniversity Institute for Biotechnology (VIB 09) and Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University. B-9000 Gent. Belgium
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58
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Rich RL, Myszka DG. A survey of the year 2002 commercial optical biosensor literature. J Mol Recognit 2004; 16:351-82. [PMID: 14732928 DOI: 10.1002/jmr.649] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We have compiled 819 articles published in the year 2002 that involved commercial optical biosensor technology. The literature demonstrates that the technology's application continues to increase as biosensors are contributing to diverse scientific fields and are used to examine interactions ranging in size from small molecules to whole cells. Also, the variety of available commercial biosensor platforms is increasing and the expertise of users is improving. In this review, we use the literature to focus on the basic types of biosensor experiments, including kinetics, equilibrium analysis, solution competition, active concentration determination and screening. In addition, using examples of particularly well-performed analyses, we illustrate the high information content available in the primary response data and emphasize the impact of including figures in publications to support the results of biosensor analyses.
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Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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Drøbak BK, Franklin-Tong VE, Staiger CJ. The role of the actin cytoskeleton in plant cell signaling. THE NEW PHYTOLOGIST 2004; 163:13-30. [PMID: 33873778 DOI: 10.1111/j.1469-8137.2004.01076.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The plant actin cytoskeleton provides a dynamic cellular component which is involved in the maintenance of cell shape and structure. It has been demonstrated recently that the actin cytoskeleton and its associated elements provide a key target in many signaling events. In addition to acting as a target, the actin cytoskeleton can also act as a transducer of signal information. In this review we describe some newly discovered aspects of the roles of the actin cytoskeleton in plant cell signaling. In addition to a summary of the roles played by actin-binding proteins, we also briefly review the progress made in understanding how the actin cytoskeleton participates in the self-incompatibility response in pollen tubes. Finally, the emerging importance of the actin cytoskeleton in the perception and responses to stimuli such as gravity, touch and cold stress exposure are discussed. Contents I. Introduction - the actin cytoskeleton 13 II. Actin-binding proteins 14 III. The actin cytoskeleton as a target and mediator of plant cell signaling 20 IV. Summary and conclusion 25 References 25 Acknowledgements 25.
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Affiliation(s)
- B K Drøbak
- Cell Signaling Group, Department of Disease and Stress Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - V E Franklin-Tong
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - C J Staiger
- Purdue Motility Group, Department of Biological Sciences, Purdue University, 333 Hansen Life Sciences Building, 201 S. University Street, West Lafayette, IN 47907-2064, USA
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Wittenmayer N, Jandrig B, Rothkegel M, Schlüter K, Arnold W, Haensch W, Scherneck S, Jockusch BM. Tumor suppressor activity of profilin requires a functional actin binding site. Mol Biol Cell 2004; 15:1600-8. [PMID: 14767055 PMCID: PMC379259 DOI: 10.1091/mbc.e03-12-0873] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Profilin 1 (PFN1) is a regulator of the microfilament system and is involved in various signaling pathways. It interacts with many cytoplasmic and nuclear ligands. The importance of PFN1 for human tissue differentiation has been demonstrated by the findings that human cancer cells, expressing conspicuously low PFN1 levels, adopt a nontumorigenic phenotype upon raising their PFN1 level. In the present study, we characterize the ligand binding site crucial for profilin's tumor suppressor activity. Starting with CAL51, a human breast cancer cell line highly tumorigenic in nude mice, we established stable clones that express PFN1 mutants differentially defective in ligand binding. Clones expressing PFN1 mutants with reduced binding to either poly-proline-stretch ligands or phosphatidyl-inositol-4,5-bisphosphate, but with a functional actin binding site, were normal in growth, adhesion, and anchorage dependence, with only a weak tendency to elicit tumors in nude mice, similar to controls expressing wild-type PFN1. In contrast, clones expressing a mutant with severely reduced capacity to bind actin still behaved like the parental CAL51 and were highly tumorigenic. We conclude that the actin binding site on profilin is instrumental for normal differentiation of human epithelia and the tumor suppressor function of PFN1.
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Affiliation(s)
- Nina Wittenmayer
- Cell Biology, Zoological Institute, Technical University of Braunschweig, D-38092 Braunschweig, Germany
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61
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Hilpelä P, Vartiainen MK, Lappalainen P. Regulation of the Actin Cytoskeleton by PI(4,5)P2 and PI(3,4,5)P3. Curr Top Microbiol Immunol 2004; 282:117-63. [PMID: 14594216 DOI: 10.1007/978-3-642-18805-3_5] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The actin cytoskeleton is fundamental for various motile and morphogenetic processes in cells. The structure and dynamics of the actin cytoskeleton are regulated by a wide array of actin-binding proteins, whose activities are controlled by various signal transduction pathways. Recent studies have shown that certain membrane phospholipids, especially PI(4,5)P2 and PI(3,4,5)P3, regulate actin filament assembly in cells and in cell extracts. PI(4,5)P2 appears to be a general regulator of actin polymerization at the plasma membrane or at membrane microdomains, whereas PI(3,4,5)P3 promotes the assembly of specialized actin filament structures in response to some growth factors. Biochemical studies have demonstrated that the activities of many proteins promoting actin assembly are upregulated by PI(4,5)P2, whereas proteins that inhibit actin assembly or promote filament disassembly are down-regulated by PI(4,5)P2. PI(3,4,5)P3 promotes its effects on the actin cytoskeleton mainly through activation of the Rho family of small GTPases. In addition to their effects on actin dynamics, both PI(4,5)P2 and PI(3,4,5)P3 promote the formation of specific actin filament structures through activation/inactivation of actin filament cross-linking proteins and proteins that mediate cytoskeleton-plasma membrane interactions.
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Affiliation(s)
- P Hilpelä
- Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, P.O. Box 56, 00014 Helsinki, Finland
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Kumar N, Zhao P, Tomar A, Galea CA, Khurana S. Association of villin with phosphatidylinositol 4,5-bisphosphate regulates the actin cytoskeleton. J Biol Chem 2003; 279:3096-110. [PMID: 14594952 DOI: 10.1074/jbc.m308878200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Villin, an epithelial cell actin-binding protein, severs actin in vitro and in vivo. Previous studies report that phosphatidylinositol 4,5-bisphosphate (PIP(2)) regulates actin severing by villin, presumably by interaction with villin. However, direct association of villin with PIP(2) has never been characterized. In this report, we presented mutational analysis to identify the PIP(2)-binding sites in villin. Villin (human) binds PIP(2) with a K(d) of 39.5 microm, a stoichiometry of 3.3, and a Hill coefficient of 1. We generated deletion mutants of villin lacking putative PIP(2)-binding sites and examined the impact of these mutations on PIP(2) binding and actin dynamics. Our analysis revealed the presence of three PIP(2)-binding sites, two in the amino-terminal core and one in the carboxyl-terminal headpiece of human villin. Synthetic peptides analogous with these sites confirmed the binding domains. Circular dichroism and quenching of intrinsic tryptophan fluorescence revealed a significant conformational change in these peptides ensuing in their association with PIP(2). By using site-directed mutagenesis (arginine 138 to alanine), we demonstrated the presence of an identical F-actin and PIP(2)-binding site in the capping and severing domain of villin. In contrast, the mutants lysine 822 and 824 to alanine demonstrated the presence of an overlapping F-actin and PIP(2)-binding site in the actin cross-linking domain of villin. Consistent with this observation, association of villin with PIP(2) inhibited the actin capping and severing functions of villin and enhanced the actin bundling function of villin. Our studies revealed that structural changes induced by association with PIP(2) could regulate the actin-modifying functions of villin. This study provided biochemical proof of the functional significance of villin association with PIP(2) and identified the molecular mechanisms involved in the regulation of actin dynamics by villin and PIP(2).
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Affiliation(s)
- Narendra Kumar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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