Functional reconstitution of mammalian ‘chloride intracellular channels’ CLIC1, CLIC4 and CLIC5 reveals differential regulation by cytoskeletal actin

  title={Functional reconstitution of mammalian ‘chloride intracellular channels’ CLIC1, CLIC4 and CLIC5 reveals differential regulation by cytoskeletal actin},
  author={H Singh and Michael A. Cousin and R Head Ashley},
  journal={The FEBS Journal},
Chloride intracellular channels (CLICs) are soluble, signal peptide‐less proteins that are distantly related to Ω‐type glutathione‐S‐transferases. Although some CLICs bypass the classical secretory pathway and autoinsert into cell membranes to form ion channels, their cellular roles remain unclear. Many CLICs are strongly associated with cytoskeletal proteins, but the role of these associations is not known. In this study, we incorporated purified, recombinant mammalian CLIC1, CLIC4 and (for… 
Emerging biological roles of Cl− intracellular channel proteins
Emerging evidence points to a role of CLIC proteins in actin dynamics and membrane trafficking and the lessons learned from gene-targeting studies are discussed.
Interaction of Human Chloride Intracellular Channel Protein 1 (CLIC1) with Lipid Bilayers: A Fluorescence Study.
It is shown that fluorescence spectroscopy can be used to establish the interaction and position of CLIC1 in a lipid bilayer and support the current model of an oxidation-driven interaction of CLic1 with lipid bilayers and also propose a membrane anchoring role for Trp35.
Identification and Characterization of a Bacterial Homolog of Chloride Intracellular Channel (CLIC) Protein
It is found that indanyloxyacetic acid-94 (IAA-94), a blocker of CLICs, delays the growth of Escherichia coli and SspA, the E. coli stringent starvation protein A, shares sequence and structural homology with CL ICs and forms functional ion channels.
CLIC 4 translocation 25 Spatiotemporal regulation of CLIC 4 , a novel player in the G α 13-RhoA signaling pathway
The results show that CLIC4 is regulated by G 13-linked RhoA pathway to be targeted to G13-coupled receptor complexes at the plasma membrane, and they suggest thatCLIC4 binds an as-yet-unknown substrate in a manner analogous to GST-substrate interaction.
Investigating Sterol and Redox Regulation of the Ion Channel Activity of CLIC1 Using Tethered Bilayer Membranes
It is shown that membrane sterols play an essential role in CLIC1’s acrobatic switching from a globular soluble form to an integral membrane form, promoting greater ion channel conductance in membranes, and that redox play a role in the ion channel activity of CLic1.
Transmembrane extension and oligomerization of the CLIC1 chloride intracellular channel protein upon membrane interaction.
Fitting the data to symmetric oligomer models of the CLIC1 transmembrane form indicates that the structure is large and most consistent with a model comprising approximately six to eight subunits.
Regulation of the Membrane Insertion and Conductance Activity of the Metamorphic Chloride Intracellular Channel Protein CLIC1 by Cholesterol
The observed cholesterol dependent behaviour of CLIC1 is highly reminiscent of the cholesterol-dependent-cytolysin family of bacterial pore-forming proteins, suggesting common regulatory mechanisms for spontaneous protein insertion into the membrane bilayer.
Both CLIC4 and CLIC5A activate ERM proteins in glomerular endothelium.
The findings indicate that CLIC4/CLIC5A-mediated ERM activation is required for maintenance of the glomerular capillary architecture.


CLIC-5A Functions as a Chloride Channel in Vitro and Associates with the Cortical Actin Cytoskeleton in Vitro and in Vivo*
It is shown that similar protein complexes can be isolated using either immobilized CLIC-5A or the C-terminal F-actin-binding domain of ezrin and that actin polymerization is required for de novo assembly of these complexes.
Challenging accepted ion channel biology: p64 and the CLIC family of putative intracellular anion channel proteins (Review)
  • R. Ashley
  • Biology
    Molecular membrane biology
  • 2003
Critical to this future work is the need for better characterization of membrane topology, careful functional analysis of reconstituted and native channels, including their conductances and selectivities, and detailed structurelfunction studies including targeted mutagenesis to investigate the structure of the putative pore, the role of protein phosphorylation and the roleof conserved cysteine residues.
Redox regulation of CLIC1 by cysteine residues associated with the putative channel pore.
The findings support a simple structural hypothesis to explain how CLIC1 oligomers form pores in membranes, and suggest that native channels may be regulated by a novel mechanism involving the formation and reduction of intersubunit disulphide bonds.
Chloride channel activity of ClC-2 is modified by the actin cytoskeleton.
It is shown in the Xenopus oocyte expression system that the chloride-channel activity of ClC-2 is enhanced after treatment with the actin-disrupting agents cytochalasin and latrunkulin, and this work suggests that electrostatic interactions between the N-terminus of Cl C-2 and theActin cytoskeleton might have a role in the regulation of this channel.
Identification of a novel member of the chloride intracellular channel gene family (CLIC5) that associates with the actin cytoskeleton of placental microvilli.
These studies suggest that CLIC1, CLIC4, and CLIC5 play distinct roles in chloride transport and thatCLIC5 interacts with the cortical actin cytoskeleton in polarized epithelial cells.
Chloride intracellular channel protein CLIC4 (p64H1) binds directly to brain dynamin I in a complex containing actin, tubulin and 14-3-3 isoforms.
It is speculated that brain CLIC4 might be involved in the dynamics of neuronal plasma membrane microdomains (micropatches) containing caveolin-like proteins and might also have other cellular roles related to membrane trafficking.
CLIC4 (p64H1) and its putative transmembrane domain form poorly selective, redox-regulated ion channels
It is suggested that oligomers containing the putative TMD are essential components of the CLIC4 pore, however, the pore is inherently non-selective, and any ionic selectivity inCLIC4 (and other membrane CLICs) may be attributable to other regions of the protein, including the channel vestibules.
Recombinant CLIC1 (NCC27) Assembles in Lipid Bilayers via a pH-dependent Two-state Process to Form Chloride Ion Channels with Identical Characteristics to Those Observed in Chinese Hamster Ovary Cells Expressing CLIC1*
This work indicates that the CLIC1 ion channel is likely to consist of a tetrameric assembly of subunits and indicates that despite its size and unusual properties, it is able to form a completely functional ion channel in the absence of any other ancillary proteins.