101
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Hilgemann DW. Local PIP(2) signals: when, where, and how? Pflugers Arch 2007; 455:55-67. [PMID: 17534652 DOI: 10.1007/s00424-007-0280-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 04/17/2007] [Indexed: 10/24/2022]
Abstract
PIP(2) is a minor phospholipid that modulates multiple cellular processes. However, its abundance by mass, like diacylglycerol, is still 20 to 100 times greater than the master phospholipid second messenger, PIP(3). Therefore, it is a case-by-case question whether PIP(2) is acting more like GTP, in being a cofactor in regulatory processes, or whether it is being used as a true second messenger. Analysis of signaling mechanisms in primary cells is essential to answer this question, as overexpression studies will naturally generate false positives. In connection with the possible messenger function of PIP(2), a second question arises as to how and if PIP(2) metabolism and signaling may be limited in space. This review summarizes succinctly the notable cases in which PIP(2) is proposed to function in a localized way and the different mechanistic models that may allow it to function locally. In general, drastic restrictions of PIP(2) diffusion are required. It is speculated that molecular PIP(2) signaling may be possible in the absence of PIP(2) gradients via ternary complexes between PIP(2) and two protein partners. That PIP(2) synthesis and hydrolysis might be locally dependent on protein-protein interactions, and direct lipid "hand-off" is suggested by multiple results.
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Affiliation(s)
- Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390-9040, USA.
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102
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Mao YS, Yin HL. Regulation of the actin cytoskeleton by phosphatidylinositol 4-phosphate 5 kinases. Pflugers Arch 2007; 455:5-18. [PMID: 17520274 DOI: 10.1007/s00424-007-0286-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Accepted: 05/02/2007] [Indexed: 12/19/2022]
Abstract
Phosphatidylinositol (4,5)-bisphosphate (PIP(2)) is an important lipid mediator that has multiple regulatory functions. There is now increasing evidence that the phosphatidylinositol 4-phosphate 5 kinases (PIP5Ks), which synthesize PIP(2), are regulated spatially and temporally and that they have isoform-specific functions and regulations. This review will summarize the highlights of recent developments in understanding how the three major PIP5K isoforms regulate the actin cytoskeleton and other important cellular processes.
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Affiliation(s)
- Yuntao S Mao
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390-9040, USA
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103
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Krauß M, Haucke V. Phosphoinositide-metabolizing enzymes at the interface between membrane traffic and cell signalling. EMBO Rep 2007; 8:241-6. [PMID: 17330069 PMCID: PMC1808040 DOI: 10.1038/sj.embor.7400919] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2006] [Accepted: 01/17/2007] [Indexed: 01/13/2023] Open
Abstract
Phosphoinositides (PIs) have long been known to have important roles in cell signalling. During the past decade, it has become clear that these lipids also act as constitutive signals that aid in defining organelle identity, and are short-lived recruiters and regulators of cytoskeletal and membrane dynamics. Recent studies have provided important clues as to how regulated activation of PI-metabolizing enzymes and recruitment of their binding proteins might cooperate in targeting distinct pools of PIs to different cell physiological functions.
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Affiliation(s)
- Michael Krauß
- Department of Membrane Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 6, 14195 Berlin, Germany
| | - Volker Haucke
- Department of Membrane Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 6, 14195 Berlin, Germany
- Tel: +49 30 838 569 22; Fax: +49 30 838 569 19;
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104
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Abstract
Because of the discovery of coated pits and vesicles more than 40 years ago and the identification of clathrin as a major component of the coat, it has been assumed that clathrin-coated pits (CCPs) are responsible for the uptake of most plasma membrane receptors undergoing internalization. The recent molecular characterization of clathrin-independent routes of endocytosis confirms that several alternative endocytic pathways operate at the plasma membrane of mammalian cells. This heterogeneous view of endocytosis has been expanded still further by recent studies, suggesting that different subpopulations of CCPs responsible for the internalization of specific sets of cargo may coexist. In the present review, we have discussed the experimental evidence in favor or against the existence of distinct parallel clathrin-dependent pathways at the plasma membrane.
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Affiliation(s)
- Alexandre Benmerah
- Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), 75014 Paris, France, and INSERM, U567, 75014 Paris, France.
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105
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Nakano-Kobayashi A, Yamazaki M, Unoki T, Hongu T, Murata C, Taguchi R, Katada T, Frohman MA, Yokozeki T, Kanaho Y. Role of activation of PIP5Kgamma661 by AP-2 complex in synaptic vesicle endocytosis. EMBO J 2007; 26:1105-16. [PMID: 17290217 PMCID: PMC1852847 DOI: 10.1038/sj.emboj.7601573] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Accepted: 01/04/2007] [Indexed: 11/09/2022] Open
Abstract
Synaptic vesicles (SVs) are retrieved by clathrin-mediated endocytosis at the nerve terminals. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] drives this event by recruiting the components of the endocytic machinery. However, the molecular mechanisms that result in local generation of PI(4,5)P2 remain unclear. We demonstrate here that AP-2 complex directly interacts with phosphatidylinositol 4-phosphate 5-kinase gamma661 (PIP5Kgamma661), the major PI(4,5)P2-producing enzyme in the brain. The beta2 subunit of AP-2 was found to bind to the C-terminal tail of PIP5Kgamma661 and cause PIP5Kgamma661 activation. The interaction is regulated by PIP5Kgamma661 dephosphorylation, which is triggered by depolarization in mouse hippocampal neurons. Finally, overexpression of the PIP5Kgamma661 C-terminal region in hippocampal neurons suppresses depolarization-dependent SV endocytosis. These findings provide evidence for the molecular mechanism through which PIP5Kgamma661 locally generates PI(4,5)P2 in hippocampal neurons and suggest a model in which the interaction trigger SV endocytosis.
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Affiliation(s)
- Akiko Nakano-Kobayashi
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
| | - Masakazu Yamazaki
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
| | - Takamitsu Unoki
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tsunaki Hongu
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
| | - Chie Murata
- Department of Metabolome, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Ryo Taguchi
- Department of Metabolome, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Toshiaki Katada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
| | - Michael A Frohman
- Center for Developmental Genetics and Department of Pharmacology, Stony Brook University, New York, NY, USA
| | - Takeaki Yokozeki
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
| | - Yasunori Kanaho
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan
- Department of Physiological Chemistry, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Ten-noudai, Tsukuba 305-0006, Japan. Tel.: +81 29 853 3282; Fax: +81 29 853 3271; E-mail:
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106
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Rich RL, Myszka DG. Survey of the year 2006 commercial optical biosensor literature. J Mol Recognit 2007; 20:300-66. [DOI: 10.1002/jmr.862] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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107
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Perera RM, Zoncu R, Lucast L, De Camilli P, Toomre D. Two synaptojanin 1 isoforms are recruited to clathrin-coated pits at different stages. Proc Natl Acad Sci U S A 2006; 103:19332-7. [PMID: 17158794 PMCID: PMC1693868 DOI: 10.1073/pnas.0609795104] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phosphoinositides are thought to play an important role in clathrin-coated pit (CCP) dynamics. Biochemical and structural studies have shown a direct interaction of phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] with endocytic clathrin adaptors, whereas functional studies using cell-free systems or intact cells have demonstrated the importance of PI(4,5)P2 synthesis and dephosphorylation in clathrin coating and uncoating, respectively. Furthermore, genetic manipulations of kinases and phosphatases involved in PI(4,5)P2 metabolism result in major defects in synaptic vesicle recycling and other forms of clathrin-dependent endocytosis. However, live imaging studies of these enzymes at CCPs have not been conducted. We have used multicolor total internal reflection fluorescence microscopy (TIRFM) to visualize the spatial-temporal recruitment of synaptojanin 1 (SJ1), a polyphosphoinositide phosphatase, and its binding partner endophilin to CCPs. Strikingly, we observed differential temporal recruitment of the two major SJ1 splice variants to CCPs. The 145-kDa isoform, the predominant isoform expressed in the brain, was rapidly recruited as a "burst," together with endophilin, at a late stage of CCP formation. In contrast, the nonneuronal ubiquitously expressed 170-kDa isoform of SJ1 was present at all stages of CCP formation. These results raise the possibility that dynamic phosphoinositide metabolism may occur throughout the lifetime of a CCP.
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Affiliation(s)
| | - Roberto Zoncu
- *Department of Cell Biology and
- Howard Hughes Medical Institute, Kavli Institute for Neuroscience and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510
| | - Louise Lucast
- *Department of Cell Biology and
- Howard Hughes Medical Institute, Kavli Institute for Neuroscience and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510
| | - Pietro De Camilli
- *Department of Cell Biology and
- Howard Hughes Medical Institute, Kavli Institute for Neuroscience and Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06510
- To whom correspondence may be addressed. E-mail:
or
| | - Derek Toomre
- *Department of Cell Biology and
- To whom correspondence may be addressed. E-mail:
or
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108
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Jeynov B, Lay D, Schmidt F, Tahirovic S, Just WW. Phosphoinositide synthesis and degradation in isolated rat liver peroxisomes. FEBS Lett 2006; 580:5917-24. [PMID: 17045591 DOI: 10.1016/j.febslet.2006.09.058] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 09/18/2006] [Accepted: 09/19/2006] [Indexed: 11/30/2022]
Abstract
Analyzing peroxisomal phosphoinositide (PId(#)) synthesis in highly purified rat liver peroxisomes we found synthesis of phosphatidylinositol 4-phosphate (PtdIns4P), PtdIns(4,5)P(2) and PtdIns(3,5)P(2). PtdIns3P was hardly detected in vitro, however, was observed in vivo after [(32)P]-phosphate labeling of primary rat hepatocytes. In comparison with other subcellular organelles peroxisomes revealed a unique PId pattern suggesting peroxisomal specificity of the observed synthesis. Use of phosphatase inhibitors enhanced the amount of PtdIns4P. The results obtained provide evidence that isolated rat liver peroxisomes synthesize PIds and suggest the association of PId 4-kinase and PId 5-kinase and PId 4-phosphatase activities with the peroxisomal membrane.
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Affiliation(s)
- Boyan Jeynov
- Biochemie-Zentrum der Universität Heidelberg (BZH), Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany
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109
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Boucrot E, Saffarian S, Massol R, Kirchhausen T, Ehrlich M. Role of lipids and actin in the formation of clathrin-coated pits. Exp Cell Res 2006; 312:4036-48. [PMID: 17097636 PMCID: PMC2785547 DOI: 10.1016/j.yexcr.2006.09.025] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 09/06/2006] [Accepted: 09/07/2006] [Indexed: 11/20/2022]
Abstract
Assembly of clathrin-coated pits and their maturation into coated vesicles requires coordinated interactions between specific lipids and several structural and regulatory proteins. In the presence of primary alcohols, phospholipase D generates phosphatidylalcohols instead of PA, reducing stimulation of phosphatidyl inositol 5-kinase (PI5K) and hence decreasing formation of phosphoinositide-4,5-biphosphate (PIP(2)). Using live-cell imaging, we have shown that acute treatment of cells with 1-butanol or other small primary alcohols induces rapid disassembly of coated pits at the plasma membrane and blocks appearance of new ones. Addition of exogenous PIP(2) reverses this effect. Coated pits and vesicles reappear synchronously upon removal of 1-butanol; we have used this synchrony to assess the role of actin in coated vesicle assembly. Prolonged inhibition of actin polymerization by latrunculin A or cytochalasin D reduced by approximately 50% the frequency of coated pit formation without affecting maturation into coated vesicles. As in control cells, removal of 1-butanol in the continued presence of an actin depolymerizer led to synchronous appearance of new pits, which matured normally. Thus, remodeling of the actin cytoskeleton is not essential for clathrin-coated vesicle assembly but may indirectly affect the nucleation of clathrin-coated pits.
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Affiliation(s)
- Emmanuel Boucrot
- Department of Cell Biology and the CBR Institute for Biomedical Research, Harvard Medical School, Boston, 200 Longwood Ave, MA 02115 USA
| | - Saveez Saffarian
- Department of Cell Biology and the CBR Institute for Biomedical Research, Harvard Medical School, Boston, 200 Longwood Ave, MA 02115 USA
| | - Ramiro Massol
- Department of Cell Biology and the CBR Institute for Biomedical Research, Harvard Medical School, Boston, 200 Longwood Ave, MA 02115 USA
| | - Tomas Kirchhausen
- Department of Cell Biology and the CBR Institute for Biomedical Research, Harvard Medical School, Boston, 200 Longwood Ave, MA 02115 USA
| | - Marcelo Ehrlich
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, Israel
- *Corresponding author. Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, Israel, Phone:972-3-6409406; Fax:972-3-6420246 E-Mail:
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