Disease relevance of CLIC4

• Whereas normal breast fibroblasts were devoid of CLIC4 protein expression, myofibroblasts of breast carcinomas were strongly CLIC4-positive [1].
• CLIC4 was expressed at high levels in resting vessels, whereas expression was modulated during pathological angiogenesis such as in tumor vessels [2].
• Introduction of CLIC4 or nuclear targeted CLIC4 via adenovirus into human breast cancer xenografts inhibited tumor growth, whereas overexpression of CLIC4 in stromal cells of xenografts enhanced tumor growth [3].
• Histamine as a growth factor and chemoattractant for human carcinoma and melanoma cells: action through Ca2(+)-mobilizing H1 receptors [4].
• BACKGROUND: Mutations in the gene encoding the human cardiac Na(+) channel alpha-subunit (hH1) are responsible for chromosome 3-linked congenital long-QT syndrome (LQT3) and idiopathic ventricular fibrillation (IVF) [5].

High impact information on CLIC4

• Histamine regulates T-cell and antibody responses by differential expression of H1 and H2 receptors [6].
• Further work will continue toward enhancing our understanding of the control by histamine of intracellular signaling via H1- and H2-receptors, and the rapid explosion of work on the H3-receptor should begin to unravel the mechanisms underlying its actions, perhaps via effects on ionic channels [7].
• Chlorpheniramine, an H1 antihistamine, did not block the histamine inhibition of granulocyte lysosomal enzyme release [8].
• In line with this, we found that PLCbeta3(-/-) mice showed significant defects in scratching behavior induced by histamine; histamine-trifluoromethyl-toluidine (HTMT), a selective H1 agonist; and compound 48/80, a mast cell activator [9].
• It is known that histone H1 and HMG proteins compete for a common binding site, the linker DNA [10].

Chemical compound and disease context of CLIC4

• BACKGROUND: Levocabastine is a selective topical H1 antagonist, effective in the treatment of seasonal allergic rhinitis and conjunctivitis [11].
• Changes in [Ca2+]i and inositol phosphate production exhibit a similar dose-response relationship for histamine (maximal effect at 10(-4) M), with both phenomena being blocked by the H1 antagonist mepyramine and being insensitive to pertussis toxin treatment [12].
• Collectively, the present study shows that histamine induced [Ca2+]i transients in PC3 human prostate cancer cells by stimulating H1 histamine receptors leading to Ca2+ release from the endoplasmic reticulum in an inositol 1,4,5-trisphosphate-dependent manner, and by inducing Ca2+ entry [13].
• With HCO3 solution, anoxic H1 efflux rate was approximately 50% of normoxia (0.333 vs. 0.645 mmol.l-1.min-1), but in TES solution, H1 efflux rate was unaffected by anoxia [14].

Biological context of CLIC4

• In a migration assay, we found that CLIC4 inhibited cell motility by 27% [1].
• These results suggest that CLIC4 is differentially regulated in fibroblasts and that its expression contributes to a collective stationary myofibroblast phenotype [1].
• Antisense- and small interfering RNA-mediated suppression of CLIC4 expression led to arrest in tubular morphogenesis [2].
• The localization of CLIC4 to the cortical actin cytoskeleton and its association with AKAP350 at the centrosome and midbody suggests that CLIC4 may be important for regulating cytoskeletal organization during the cell cycle [15].
• Quantitative proteomic analysis of myc-induced apoptosis: a direct role for Myc induction of the mitochondrial chloride ion channel, mtCLIC/CLIC4 [16].

Anatomical context of CLIC4

• Immunoblot analysis of extracts from placental tissues demonstrated that CLIC4 and CLIC5 are enriched in isolated placental microvilli, whereas CLIC1 is not [17].
• Indirect immunofluorescence microscopy revealed that CLIC4 and CLIC5 are concentrated within the apical region of the trophoblast, whereas CLIC1 is distributed throughout the cytoplasm [17].
• The subcellular localization of CLIC4 in endothelial cells was dependent on whether cells were engaged in proliferation or tube formation [2].
• In this report, we show that endogenous CLIC4 and AKAP350 colocalize at the centrosome and midbody of cultured cells by immunofluorescence microscopy [15].
• CLIC4 is enriched at cell-cell junctions and colocalizes with AKAP350 at the centrosome and midbody of cultured mammalian cells [15].

Associations of CLIC4 with chemical compounds

• One of the clones, identified as CLIC4, a member of the CLIC family of chloride channels, was up-regulated more than 16 times in myofibroblasts and was therefore chosen for further analysis [1].
• The functional significance of CLIC4 was analyzed in MEF/3T3 fibroblasts by conditional expression using the tetracycline-repressive gene regulation system [1].
• Reduction of CLIC4 and several other CLIC family members by expressing a doxycycline-regulated CLIC4 antisense also causes apoptosis in squamous cancer cell lines [18].
• Staurosporine, a potent protein kinase C inhibitor, blocked GVBD and the activation of M-phase-specific H1 kinase, whereas HA1004, which preferentially antagonizes protein kinase A, had no effect [19].
• After 24-h histamine treatment, known to desensitize H1 receptors, reapplication of histamine increased cell coupling in a way prevented by ranitidine, an H2 receptor blocker [20].

Regulatory relationships of CLIC4

• Proteomic analysis of vascular endothelial growth factor-induced endothelial cell differentiation reveals a role for chloride intracellular channel 4 (CLIC4) in tubular morphogenesis [2].
• The silencer, a negative cis-acting element of the AFP gene, was highly activated in huH-1 and HepG2 to repress AFP enhancer activity by 91%, whereas only 26% repression was observed in HuH-7 [21].

Other interactions of CLIC4

• Differential expression of a chloride intracellular channel gene, CLIC4, in transforming growth factor-beta1-mediated conversion of fibroblasts to myofibroblasts [1].
• It has been previously shown that a 14-amino acid (aa) modified peptide (H1-S6A,F8A) derived from the helix 1 (H1) carboxylic region of c-Myc can interfere in vitro with specific c-Myc DNA binding [22].
• We used a polymerase chain reaction-based approach to identify candidate genes in mammalian brain and cloned the cDNA corresponding to rat brain p64H1 [23].
• We considered that the histamine-1 (H1) receptor antagonist hydroxyzine, which also partially inhibits brain mast cells and has anxiolytic properties, may reduce MS symptoms [24].
• In huH-1 and HuH-7, both ATBF1 isoforms suppressed strongly enhancer activity and slightly promoter activity [21].

Analytical, diagnostic and therapeutic context of CLIC4

• Northern blot analysis showed that CLIC5 has a distinct pattern of expression compared with CLIC1 and CLIC4 [17].
• Immunohistochemistry showed a hitherto unknown, distinctive pattern of CLIC4 expression in breast stroma [1].
• Immunogold electron microscopy and confocal analyses indicate that nuclear CLIC4 is detected prior to the apoptotic phenotype [25].
• RESULTS: In cDNA arrays of matched human normal and tumor tissues, CLIC4 expression was reduced in renal, ovarian, and breast cancers [3].
• Coculture of cancer cells and fibroblasts induced the expression of both CLIC4 and alpha-smooth muscle actin in fibroblasts adjacent to tumor nests [3].

References