CRP1, a LIM Domain Protein Implicated in Muscle Differentiation, Interacts with α-Actinin

Pomiès, Pascal; Louis, Heather A.; Beckerle, Mary C.

doi:10.1083/jcb.139.1.157

Cited by 129 publications

(145 citation statements)

References 45 publications

(80 reference statements)

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“…These proteins include cofilin, which depolymerizes actin filaments from its pointed end thereby increasing actin dynamics (54); F-actin capping protein Z and capping protein ␣2, which bind to the barbed end of actin filaments (54); neurabin 2, which binds to actin and recruits protein phosphatase to actin that controls actin rearrangement (55); the LIM and SH3 domain-containing protein, which is proposed to play important roles in the regulation of dynamic actin-based, cytoskeletal activities (56). Another LIM domain containing protein present in the PSD fraction, the cysteine rich protein, has been shown to interact with the actin cytoskeleton and may be involved in muscle differentiation (57). Tropomodulin lowers the apparent affinity of pointed ends of the actin filament for actin monomers (58).…”

Section: Discussionmentioning

confidence: 99%

Proteomics Analysis of Rat Brain Postsynaptic Density

Hornshaw

Schors

et al. 2004

Journal of Biological Chemistry

235

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The postsynaptic density contains multiple protein complexes that together relay the presynaptic neurotransmitter input to the activation of the postsynaptic neuron. In the present study we took two independent proteome approaches for the characterization of the protein complement of the postsynaptic density, namely 1) two-dimensional gel electrophoresis separation of proteins in conjunction with mass spectrometry to identify the tryptic peptides of the protein spots and 2) isolation of the trypsin-digested sample that was labeled with isotope-coded affinity tag, followed by liquid chromatography-tandem mass spectrometry for the partial separation and identification of the peptides, respectively. Functional grouping of the identified proteins indicates that the postsynaptic density is a structurally and functionally complex organelle that may be involved in a broad range of synaptic activities. These proteins include the receptors and ion channels for glutamate neurotransmission, proteins for maintenance and modulation of synaptic architecture, sorting and trafficking of membrane proteins, generation of anaerobic energy, scaffolding and signaling, local protein synthesis, and correct protein folding and breakdown of synaptic proteins. Together, these results imply that the postsynaptic density may have the ability to function (semi-) autonomously and may direct various cellular functions in order to integrate synaptic physiology.The majority of excitatory neurotransmission in the brain occurs via glutamatergic synapses. In the presynaptic element of the synapse, specialized secretion machinery determines the activity-dependent membrane fusion of glutamate-containing vesicles and the release of transmitter into the synaptic cleft. In the postsynaptic element, glutamate receptors and downstream signal transduction are organized by the protein assembly of the postsynaptic density (PSD). 1 Both the presynaptic release machinery and the PSD are electron-dense assemblies (1, 2), in which proteins are thought to be organized into distinct functional complexes (3-5) that may be dynamically regulated by neuronal activity (6 -8). The modulation of this molecular architecture of the synapse is at the basis of synaptic plasticity (6 -8), and aberrations thereof may underlie neuronal disorders.In view of the importance of the PSD in glutamatergic neurotransmission and its involvement in neuroplasticity, considerable efforts have been made to identify its protein constituents as a prelude to understand the molecular basis of PSD functioning. In the past several years, yeast two-hybrid technology has been extensively used to characterize proteins that interact with the glutamate receptors and may constitute core elements of the PSD involved in the regulation of receptor trafficking and signaling (reviewed in Refs. 9 -11). Based largely on these studies a protein-protein interaction map of the PSD has emerged. In brief, the model posits that the postsynaptic receptor complexes are localized by scaffolding proteins such as the s...

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Section: Discussionmentioning

confidence: 99%

Proteomics Analysis of Rat Brain Postsynaptic Density

Hornshaw

Schors

et al. 2004

Journal of Biological Chemistry

235

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“…Both proteins have regions with recognizable similarity to EF hands, but none of these regions seems likely to be functional for Ca 2ϩ binding (Strynadka and James, 1989), so that neither Ain1p nor Fim1p seems likely to be regulated by Ca 2ϩ . ␣-Actinins have been found to bind phosphatidylinositol 4,5-bisphosphate and to interact with several proteins, including CRP1, integrin, vinculin, and zyxin (Fukami et al, 1996;Pomiès et al, 1997; and references cited therein). Ain1p has one possible phosphatidylinositol 4,5-bisphosphate binding site, and a CRP1 homologue (accession number Q14014) has been identified by the genome project, so that these elements may be important in the regulation of Ain1p.…”

Section: Possible Regulation Of Ain1p and Fim1pmentioning

confidence: 99%

Roles of a Fimbrin and an α-Actinin-like Protein in Fission Yeast Cell Polarization and Cytokinesis

Bähler

Pringle

2001

MBoC

145

183

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Eukaryotic cells contain many actin-interacting proteins, including the ␣-actinins and the fimbrins, both of which have actin cross-linking activity in vitro. We report here the identification and characterization of both an ␣-actinin-like protein (Ain1p) and a fimbrin (Fim1p) in the fission yeast Schizosaccharomyces pombe. Ain1p localizes to the actomyosin-containing medial ring in an F-actindependent manner, and the Ain1p ring contracts during cytokinesis. ain1 deletion cells have no obvious defects under normal growth conditions but display severe cytokinesis defects, associated with defects in medial-ring and septum formation, under certain stress conditions. Overexpression of Ain1p also causes cytokinesis defects, and the ain1 deletion shows synthetic effects with other mutations known to affect medial-ring positioning and/or organization. Fim1p localizes both to the cortical actin patches and to the medial ring in an F-actin-dependent manner, and several lines of evidence suggest that Fim1p is involved in polarization of the actin cytoskeleton. Although a fim1 deletion strain has no detectable defect in cytokinesis, overexpression of Fim1p causes a lethal cytokinesis defect associated with a failure to form the medial ring and concentrate actin patches at the cell middle. Moreover, an ain1 fim1 double mutant has a synthetical-lethal defect in medial-ring assembly and cell division. Thus, Ain1p and Fim1p appear to have an overlapping and essential function in fission yeast cytokinesis. In addition, protein-localization and mutant-phenotype data suggest that Fim1p, but not Ain1p, plays important roles in mating and in spore formation. INTRODUCTIONThe actin cytoskeleton is involved in many processes in eukaryotic cells, including the polarization of cell growth and cytokinesis. These many roles involve the interaction of actin with a wide variety of actin-binding proteins, including proteins that can cross-link actin filaments into isotropic gels or bundles. Many actin cross-linking proteins have been purified and studied in vitro, but their functions in vivo remain poorly understood (reviewed by Matsudaira, 1994a;Otto, 1994;Furukawa and Fechheimer, 1997;Ayscough, 1998;Bartles, 2000).Among the actin cross-linking proteins, one of the best characterized is ␣-actinin. It was first isolated from rabbit skeletal muscle (Ebashi and Ebashi, 1965) and has subsequently been identified in both muscle and nonmuscle cells from a variety of animals, in Acanthamoeba, and in Dictyostelium (Furukawa and Fechheimer, 1997;Critchley and Flood, 1999). ␣-Actinin forms a homodimer of antiparallel polypeptides (Critchley and Flood, 1999;Djinovic-Carugo et al., 1999), with the actin-binding domain of each polypeptide close to the NH 2 terminus, followed by four spectrin-like repeats and two COOH-terminal EF-hand motifs. Skeletal muscle isoforms are localized to the Z-disk and are not regulated by Ca 2ϩ , whereas nonmuscle isoforms are localized to focal adhesions, stress fibers, and other structures and are typically regulated by C...

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“…In the cytoskeleton, CRP interacts with the focal adhesion-associated LIM protein zyxin, via a LIM-LIM interaction (8). CRP and zyxin also bind the actin-binding protein ␣-actinin (19,20). These overlapping CRP-zyxin-␣-actinin interactions may either stabilize or regulate the cytoskeleton.…”

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confidence: 99%

Characterization of Two Isoforms of the Skeletal Muscle LIM Protein 1, SLIM1

Brown¹,

Mcgrath²,

Ooms³

et al. 1999

Journal of Biological Chemistry

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We have cloned and characterized a novel isoform of the skeletal muscle LIM protein 1 (SLIM1), designated SLIMMER. SLIM1 contains an N-terminal single zinc finger followed by four LIM domains. SLIMMER is identical to SLIM1 over the first three LIM domains but contains a novel C-terminal 96 amino acids with three potential bipartite nuclear localization signals, a putative nuclear export sequence, and 27 amino acids identical to the RBP-J binding region of KyoT2, a murine isoform of SLIM1. SLIM1 localized to the cytosol of Sol8 myoblasts and myotubes. SLIMMER was detected in the nucleus of myoblasts and, following differentiation into myotubes, was exclusively cytosolic. Recombinant green fluorescent protein-SLIM1 localized to the cytoplasm and associated with focal adhesions and actin filaments in COS-7 cells, while green fluorescent protein-SLIMMER was predominantly nuclear. SLIMMER truncation mutants revealed that the first nuclear localization signal mediates nuclear localization. The addition of the proposed nuclear export sequence decreased the level of exclusively nuclear expression and increased cytosolic SLIMMER expression in COS-7 cells. The leucine-rich nuclear export signal was required for the export of SLIMMER from the nucleus of myoblasts to the cytoplasm of myotubes. Collectively, these results suggest distinct roles for SLIM1 and SLIMMER in focal adhesions and nuclear-cytoplasmic communication.The LIM domain is a double zinc finger motif that mediates the protein-protein interactions of transcription factors, signaling, and cytoskeleton-associated proteins (1-4). LIM is an acronym of the three transcription factors, Lin-11, Isl-1, and Mec-3, in which the motif was first identified (5). The LIM domain contains 50 -60 amino acids, with the consensus sequence (CX 2 CX 17-19 HX 2 C)X 2 (CX 2 CX 16 -20 CX 2 (H/D/C)). The conserved cysteine and histidine residues form two zinc-binding pockets stabilizing the tertiary structure of the protein (6, 7). Despite their structural resemblance to GATA-1 zinc fingers, there is no evidence that LIM domains bind DNA directly. Instead, an increasing number of studies implicate LIM domains in protein-protein interactions that regulate development, cellular differentiation, and the cytoskeleton (8, 9).It has been proposed that LIM proteins form a scaffold upon which the coordinated assembly of proteins occurs (8,10). No single LIM domain-binding motif has been identified. LIM domains can associate with other LIM domains to form homoor heterodimers (8, 11). In addition, LIM domains also bind tyrosine-containing motifs, PDZ domains, ankyrin repeats, and helix-loop-helix domains in proteins lacking LIM domains including tyrosine and serine/threonine kinases, cytoskeletal proteins, and transcription factors (12)(13)(14)(15)(16).LIM proteins have been demonstrated in both the nucleus and cytoplasm. LIM homeodomain and LMO proteins are nuclear proteins, which regulate transcription by forming complexes with other transcription factors (2, 10). Members of the cysteine-rich...

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CRP1, a LIM Domain Protein Implicated in Muscle Differentiation, Interacts with α-Actinin

Cited by 129 publications

References 45 publications

Proteomics Analysis of Rat Brain Postsynaptic Density

Proteomics Analysis of Rat Brain Postsynaptic Density

Roles of a Fimbrin and an α-Actinin-like Protein in Fission Yeast Cell Polarization and Cytokinesis

Characterization of Two Isoforms of the Skeletal Muscle LIM Protein 1, SLIM1

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