[Show abstract][Hide abstract] ABSTRACT: Mutations of the PTEN-induced putative kinase 1 (PINK1) gene are a cause of autosomal recessive forms of Parkinson's disease. Recent studies have revealed that PINK1 is an essential factor for controlling mitochondrial quality, and that it protects cells from oxidative stresses. Although there has been considerable progress in the elucidation of various aspects of PINK1 protein regulation such as activation, stability and degradation, the transcriptional regulation of PINK1 mRNA under stress conditions remains unclear. In this study, we found that nuclear factor (erythroid-derived 2)-like 2 (NRF2), an antioxidant transcription factor, regulates PINK1 expression under oxidative stress conditions. Damaged mitochondria arising from stress conditions induced NRF2-dependent transcription of the PINK1 gene through production of reactive oxygen species (ROS). Either an ROS scavenger or forced expression of KEAP1, a potent inhibitory partner to NRF2, restricted PINK1 expression induced by activated NRF2. Transcriptionally up-regulated PINK1 diminished oxidative stress-associated cell death. The results indicate that PINK1 expression is positively regulated by NRF2 and that the NRF2-PINK1 signaling axis is deeply involved in cell survival.
PLoS ONE 11/2015; 10(11):e0142438. DOI:10.1371/journal.pone.0142438 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The receptor for advanced glycation end products (RAGE) is involved in the pathogenesis of many inflammatory, degenerative and hyper-proliferative diseases including cancer. Previously, we revealed mechanisms of downstream signaling from ligand-activated RAGE, which recruits TIRAP/MyD88. Here, we showed that DNAX-activating protein 10 (DAP10), a transmembrane adaptor protein, also binds to RAGE. By artificial oligomerization of RAGE alone or RAGE-DAP10, we found that RAGE-DAP10 heterodimer formation resulted in marked enhancement of Akt activation, whereas homo-multimeric interaction of RAGE led to activation of caspase 8. Normal human epidermal keratinocytes (NHKs) exposed to S100A8/A9, a ligand for RAGE, at a nanomolar concentration mimicked the pro-survival response of RAGE-DAP10 interaction, while at a micromolar concentration the cells mimicked the pro-apoptotic response of RAGE-RAGE. In transformed epithelial cell lines, A431 and HaCaT, in which endogenous DAP10 was overexpressed, S100A8/A9 even at a micromolar concentration led to cell growth and survival due to RAGE-DAP10 interaction. Functional blocking of DAP10 in the cell lines abrogated the Akt-phosphorylation from S100A8/A9-activated RAGE, eventually leading to an increase in apoptosis. Finally, S100A8/A9, RAGE, and DAP10 were overexpressed in the psoriatic epidermis. Our findings indicate that functional interaction between RAGE and DAP10 coordinately regulates S100A8/A9-mediated survival and/or apoptotic response of keratinocytes.
[Show abstract][Hide abstract] ABSTRACT: For expression of genes in mammalian cells, various vectors have been developed using promoters including CMV, EF-1α, and CAG promoters and have been widely used. However, such expression vectors sometimes fail to attain sufficient expression levels depending on the nature of cargo genes and/or on host cell types. In the present study, we aimed to develop a potent promoter system that enables high expression levels of cargo genes ubiquitously in many different cell types. We found that insertion of an additional promoter downstream of a cargo gene greatly enhanced the expression levels. Among the constructs we tested, C-TSC cassette (C: CMV-RU5' located upstream; TSC: another promoter unit composed of triple tandem promoters, hTERT, SV40, and CMV, located downstream of the cDNA plus a polyadenylation signal) had the most potent capability, showing far higher efficiency than that of potent conventional vector systems. The results indicate that the new expression system is useful for production of recombinant proteins in mammalian cells and for application as a gene therapeutic measure.
[Show abstract][Hide abstract] ABSTRACT: REIC/Dkk-3 is down-regulated in a broad range of human cancer cells and is considered to function as a tumor suppressor. We previously reported that REIC/Dkk-3-expressing adenovirus vector (Ad-REIC) induced endoplasmic reticulum (ER) stress and cancer-specific apoptosis in human prostate cancer. In this study, we examined the therapeutic impact of Ad-REIC on non-small cell lung cancer (NSCLC).
We examined the anti-tumor effect of Ad-REIC on 25 NSCLC cell lines in vitro and A549 cells in vivo. Two of these cell lines were artificially established as EGFR-tyrosine kinase inhibitor (TKI) resistant sublines.
Ad-REIC-treatment inhibited the cell viability by 40% or more in 13 (52%) of the 25 cell lines at multiplicity of infection (MOI) of 20 (20 MOI). These cell lines were regarded as being highly sensitive cells. The cell viability of a non-malignant immortalized cell line, OUMS-24, was not inhibited at 200 MOI of Ad-REIC. The effects of Ad-REIC on EGFR-TKI resistant sublines were equivalent to those in the parental cell lines. Here, we demonstrated that Ad-REIC treatment activated c-Jun N-terminal kinase (JNK) in NSCLC cell lines, indicating the induction of ER stress with GRP78/BiP (GRP78) up-regulation and resulting in apoptosis. A single intratumoral injection of Ad-REIC significantly inhibited the tumorigenic growth of A549 cells in vivo. As predictive factors of sensitivity for Ad-REIC treatment in NSCLC, we examined the expression status of GRP78 and coxsackievirus and adenovirus receptor (CAR). We found that the combination of the GRP78 and CAR expressional statuses may be used as a predictive factor for Ad-REIC sensitivity in NSCLC cells.
Ad-REIC induced JNK activation and subsequent apoptosis in NSCLC cells. Our study indicated that Ad-REIC has therapeutic potential against NSCLC and that the expression statuses of GRP78 and CAR may predict a potential therapeutic benefit of Ad-REIC.
PLoS ONE 02/2014; 9(2):e87900. DOI:10.1371/journal.pone.0087900 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gene expression systems with various promoters, including the cytomegalovirus (CMV) promoter, have been developed to increase the gene expression in a variety of normal and cancer cells. In particular, in the clinical trials of cancer gene therapy, a more efficient and robust gene expression system is required to achieve sufficient therapeutic outcomes. By inserting the triple translational enhancer sequences of human telomerase reverse transcriptase (hTERT), Simian virus 40 (SV40) and CMV downstream of the sequence of the BGH polyA, we were able to develop a novel gene expression system that significantly enhances the expression of the genes of interest. We termed this novel gene expression cassette the super gene expression (SGE) system, and herein verify the utility of the SGE cassette for a replication-deficient adenoviral vector. We newly developed an adenoviral vector expressing the tumor suppressor, reduced expression in immortalized cells (REIC)/Dickkopf-3 (Dkk-3), based on the CMV promoter-driven SGE system (Ad-SGE-REIC) and compared the therapeutic utility of Ad-SGE-REIC with that of the conventional adenoviral vectors (Ad-CMV-REIC or Ad-CAG-REIC). The results demonstrated that the CMV promoter-SGE system allows for more potent gene expression, and that the Ad-SGE-REIC is superior to conventional adenoviral systems in terms of the REIC protein expression and therapeutic effects. Since the SGE cassette can be applied for the expression of various therapeutic genes using various vector systems, we believe that this novel system will become an innovative tool in the field of gene expression and gene therapy.
[Show abstract][Hide abstract] ABSTRACT: The receptor for advanced glycation end products (RAGE) is a multi‑ligand cell surface receptor and a member of the immunoglobulin superfamily. RAGE is involved in a wide range of inflammatory, degenerative and hyper‑proliferative disorders which span over different organs by engaging diverse ligands, including advanced glycation end products, S100 family proteins, high‑mobility group protein B1 (HMGB1) and amyloid β. We previously demonstrated that the cytoplasmic domain of RAGE is phosphorylated upon the binding of ligands, enabling the recruitment of two distinct pairs of adaptor proteins, Toll‑interleukin 1 receptor domain‑containing adaptor protein (TIRAP) and myeloid differentiation protein 88 (MyD88). This engagement allows the activation of downstream effector molecules, and thereby mediates a wide variety of cellular processes, such as inflammatory responses, apoptotic cell death, migration and cell growth. Therefore, inhibition of the binding of TIRAP to RAGE may abrogate intracellular signaling from ligand‑activated RAGE. In the present study, we developed inhibitor peptides for RAGE signaling (RAGE‑I) by mimicking the phosphorylatable cytosolic domain of RAGE. RAGE‑I was efficiently delivered into the cells by polyethylenimine (PEI) cationization. We demonstrated that RAGE‑I specifically bound to TIRAP and abrogated the activation of Cdc42 induced by ligand‑activated RAGE. Furthermore, we were able to reduce neuronal cell death induced by an excess amount of S100B and to inhibit the migration and invasion of glioma cells in vitro. Our results indicate that RAGE‑I provides a powerful tool for therapeutics to block RAGE‑mediated multiple signaling.
International Journal of Molecular Medicine 08/2013; 32(4). DOI:10.3892/ijmm.2013.1467 · 2.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mutations in PTEN-induced putative kinase 1 (PINK1) or parkin cause autosomal recessive forms of Parkinson's disease. Recent works have suggested that loss of mitochondrial membrane potential stabilizes PINK1 and that accumulated PINK1 recruits Parkin from the cytoplasm to mitochondria for elimination of depolarized mitochondria, which is known as mitophagy. In this study, we found that PINK1 forms a complex with SARM1 and TRAF6, which is important for import of PINK1 in the outer membrane and stabilization of PINK1 on depolarized mitochondria. SARM1, which is known to be adaptor protein for Toll-like receptor, bound to PINK1 and promoted TRAF6-mediated lysine-63 chain ubiquitination of PINK1 at lysine 433. Down-regulation of SARM1 and TRAF6 abrogated accumulation of PINK1 followed by recruitment of Parkin to damaged mitochondria. Some pathogenic mutations of PINK1 reduce the complex formation and ubiqutination. These results indicate that the association of PINK1 with SARM1 and TRAF6 is an important step for mitophagy.
Molecular biology of the cell 07/2013; 24(18). DOI:10.1091/mbc.E13-01-0016 · 4.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the continuing study directed toward the development of peroxisome proliferator-activated receptor gamma (hPPARγ) agonist, we attempted to improve the water solubility of our previously developed hPPARγ-selective agonist 3, which is insufficiently soluble for practical use, by employing two strategies: introducing substituents to reduce its molecular planarity and decreasing its hydrophobicity via replacement of the adamantyl group with a heteroaromatic ring. The first approach proved ineffective, but the second was productive. Here, we report the design and synthesis of a series of α-benzyl phenylpropanoic acid-type hPPARγ partial agonists with improved aqueous solubility. Among them, we selected (R)-7j, which activates hPPARγ to the extent of about 65% of the maximum observed with a full agonist, for further evaluation. The ligand-binding mode and the reason for the partial-agonistic activity are discussed based on X-ray-determined structure of the complex of hPPARγ ligand-binding domain (LBD) and (R)-7j with previously reported ligand-LDB structures. Preliminal apoptotic effect of (R)-7j against human scirrhous gastric cancer cell line OCUM-2MD3 is also described.
[Show abstract][Hide abstract] ABSTRACT: Cellular migration is a fundamental process linked to cancer metastasis. Growing evidence indicates that the receptor for advanced glycation end products (RAGE) plays a pivotal role in this process. With regard to downstream signal transducers of RAGE, diaphanous-1 and activated small guanine nucleotide triphosphatases, Rac1 and Cdc42, have been identified. To obtain precise insight into the direct downstream signaling mechanism of RAGE, we screened for proteins interacting with the cytoplasmic domain of RAGE employing an immunoprecipitation-liquid chromatography coupled with an electrospray tandem mass spectrometry system. In the present study, we found that the cytoplasmic domain of RAGE interacted with an atypical DOCK180-related guanine nucleotide exchange factor, dedicator of cytokinesis protein 7 (DOCK7). DOCK7 bound to the RAGE cytoplasmic domain and transduced a signal to Cdc42, resulting in the formation of abundant highly branched filopodia-like protrusions, dendritic pseudopodia. Blocking of the function of DOCK7 greatly abrogated the formation of dendritic pseudopodia and suppressed cellular migration. These results indicate that DOCK7 functions as an essential and downstream regulator of RAGE-mediated cellular migration through the formation of dendritic pseudopodia.
[Show abstract][Hide abstract] ABSTRACT: The calcium binding proteins S100A8 and S100A9 can dimerize to form calprotectin, the release of which during tissue damage has been implicated in inflammation and metastasis. However, receptor(s) mediating the physiological and pathophysiological effects of this damage-associated 'danger signal' are uncertain. In this study, searching for candidate calprotectin receptors by affinity isolation-mass spectrometry, we identified the cell surface glycoprotein EMMPRIN/BASIGIN (CD147/BSG). EMMPRIN specifically bound to S100A9 but not S100A8. Induction of cytokines and matrix metalloproteases (MMPs) by S100A9 was markedly downregulated in melanoma cells by attenuation of EMMPRIN. We found that EMMPRIN signaled utilized the TNF receptor-associated factor TRAF2 distinct from the known S100 binding signaling pathway mediated by RAGE (AGER). S100A9 strongly promoted migration when EMMPRIN was highly expressed, independent of RAGE, whereas EMMPRIN blockade suppressed migration by S100A9. Immunohistological analysis of melanomas revealed that EMMPRIN was expressed at both the invasive edge of lesions as well as the adjacent epidermis, where S100A9 was also strongly expressed. In epidermal-specific transgenic mice, tail vein-injected melanoma accumulated in skin expressing S100A9 but not S100A8. Together, our results establish EMMPRIN as a receptor for S100A9 and suggest the therapeutic utility in targeting S100A9-EMMPRIN interactions.
Cancer Research 11/2012; 73(1). DOI:10.1158/0008-5472.CAN-11-3843 · 9.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The biodistribution and safety of adenoviral vectors encoding the human REIC/Dkk-3 tumor suppressor gene (Ad-REIC) were examined in this preclinical study for in situ prostate cancer gene therapy. First, the in vitro apoptotic effects of Ad-REIC in normal and cancer cells derived from the prostate and liver were examined. Significant apoptotic effects were observed at 100 MOI (multiplicity of infection) in prostate cancer cells (LNCaP, PC3) and hepatoma cells (HEP3B and HEPG2); however, no effects were seen in normal cells. To analyze the safety of intraprostatic Ad-REIC administration, the biodistribution and histology after Ad-REIC injection were evaluated in various organs of normal male C57BL6 mice. In a supporting study, vector dissemination following intravenous injection of Ad-REIC into tail veins was determined. To evaluate whether Ad-REIC was present in the collected tissue specimens, human REIC gene detection was performed using DNA-PCR. Intraprostatic treatment administered at lower doses showed vector biodistribution into the colon, urinary bladder and prostate. At higher doses, vector dissemination was observed in tissues more distant from the prostate, including the lung, thymus, heart, liver and adrenal gland. After intravenous injection of Ad-REIC, dissemination was observed in the liver and spleen. These results indicate that the biodistribution of Ad-REIC is determined by the dose and route of administration. Although acute inflammatory effects were observed in the prostate after intraprostatic administration at higher doses, no abnormal histological findings were noted in the other tissues, including those of intravenously treated mice. Regarding the safety of Ad-REIC administration, no deaths and no signs of toxicity or unusual behavior were observed in the mice in any treatment group. Based on these preclinical experiments, adenovirus-mediated in situ REIC/Dkk-3 gene therapy is considered to be safe for use as a treatment for human prostate cancer.
[Show abstract][Hide abstract] ABSTRACT: Bladder cancer is one of the most common urogenital malignancies. The intravesical instillation of anticancer agents is an attractive strategy to treat a superficial lesion or floating/disseminated cancer cells after transurethral operation. An adenovirus carrying REIC/Dkk-3, a tumor suppressor gene (Ad-REIC), exhibits cancer-specific apoptotic effects in various types of cancer cells. The aim of the present study was to examine the potential of Ad-REIC as a therapeutic agent for bladder cancer. KK47 and RT4 human bladder cancer cells were sensitive to the Ad-REIC treatment for apoptosis induction, but some human bladder cancer cell lines (T24, J82 and TccSup) were resistant. Significant cell growth inhibition was observed when these resistant cancer cell lines were treated with Ad-REIC in a condition of floating cells, which is clinically observed after transurethral operation and becomes a cause of intravesical cancer dissemination. The therapeutic potential of Ad-REIC for the treatment of multidrug-resistant bladder cancer was investigated. The adriamycin-resistant KK47 bladder cancer cells (KK47/ADM), which also present multidrug resistance, showed induction of significant apoptosis following Ad-REIC treatment. The Ad-REIC treatment induced downregulation of P-glycoprotein in KK47/ADM cells and restored the sensitivity to doxorubicin (adriamycin). Ad-REIC suppressed P-glycoprotein expression in a c-Jun-NH2-kinase (JNK)-dependent manner. Therefore, the current study indicated two therapeutic aspects of the Ad-REIC agent against human bladder cancer cells, as an apoptosis inducer/cell growth inhibitor and as a sensitizer of chemotherapeutic agents in multidrug-resistant cancer cells. The intravesical instillation of Ad-REIC could be an attractive therapeutic method in human bladder cancer where the treatment of superficial lesions and floating/disseminated or multidrug-resistant cancer cells is necessary.
International Journal of Oncology 05/2012; 41(2):559-64. DOI:10.3892/ijo.2012.1503 · 3.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Osteosarcoma is the most common malignant tumor of bone in childhood and adolescence. Despite intensive research for new therapies, the outcome in patients with metastasis remains extremely poor. S100 proteins are involved in the proliferation, cell cycle progression and metastasis of numerous malignant tumors, including osteosarcoma. In the present study, we identified S100A7 as a candidate to promote the migration of osteosarcoma cells. S100A7 promoted the migration and invasion of osteosarcoma cells as assayed in vitro. An in vitro pull-down assay revealed the binding of the recombinant S100A7 protein with its putative receptor, the receptor for advanced glycation end products (RAGE). The downregulation of RAGE by a specific siRNA markedly suppressed the migration and invasion of osteosarcoma cells. Furthermore, the matrix metalloproteinase activity of osteosarcoma cells was enhanced by S100A7 and suppressed by the downregulation of RAGE. These results indicate that S100A7 promotes the migration and invasion of osteosarcoma cells through RAGE. The S100A7-RAGE axis may thus be a new target for preventing the invasion and/or metastasis of osteosarcoma.
[Show abstract][Hide abstract] ABSTRACT: The preclinical safety and therapeutic efficacy of adenoviral vectors that express the REIC/Dkk-3 tumor suppressor gene (Ad-REIC) was examined for use in prostate cancer gene therapy. The Ad-human (h) and mouse (m) REIC were previously demonstrated to induce strong anti-cancer effects in vitro and in vivo, and we herein report the results of two in vivo studies. First, intra-tumor Ad-hREIC administration was examined for toxicity and therapeutic effects in a subcutaneous tumor model using the PC3 prostate cancer cell line. Second, intra-prostatic Ad-mREIC administration was tested for toxicity in normal mice. The whole-body and spleen weights, hematological and serum chemistry parameters, and histological evaluation of tissues from throughout the body were analyzed. Both experiments indicated that there was no significant difference in the examined parameters between the Ad-REIC-treated group and the control (PBS- or Ad-LacZ-treated) group. In the in vitro analysis using PC3 cells, a significant apoptotic effect was observed after Ad-hREIC treatment. Confirming this observation, the robust anti-tumor efficacy of Ad-hREIC was demonstrated in the in vivo subcutaneous prostate cancer model. Based on the results of these preclinical experiments, we consider the adenovirus-mediated REIC/Dkk-3 in situ gene therapy to be safe and useful for the clinical treatment of prostate cancer.
[Show abstract][Hide abstract] ABSTRACT: The REIC (reduced expression in immortalized cells)/Dkk-3 is down-regulated in various cancers and considered to be a tumor suppressor gene. REIC/Dkk-3 mRNA has two isoforms (type-a,b). REIC type-a mRNA has shown to be a major transcript in various cancer cells, and its promoter activity was much stronger than that of type-b. In this study, we examined the methylation status of REIC/Dkk-3 type-a in a broad range of human malignancies.
We examined REIC/Dkk-3 type-a methylation in breast cancers, non-small-cell lung cancers, gastric cancers, colorectal cancers, and malignant pleural mesotheliomas using a quantitative combined bisulfite restriction analysis assay and bisulfate sequencing. REIC/Dkk-3 type-a and type-b expression was examined using reverse transcriptional PCR. The relationships between the methylation and clinicopathological factors were analyzed.
The rate of REIC/Dkk-3 type-a methylation ranged from 26.2 to 50.0% in the various primary tumors that were examined. REIC/Dkk-3 type-a methylation in breast cancer cells was significantly heavier than that in the other cell lines that we tested. REIC/Dkk-3 type-a methylation was inversely correlated with REIC/Dkk-3 type-a expression. There was a correlation between REIC/Dkk-3 type-a and type-b mRNA expression. REIC/Dkk-3 type-a expression was restored in MDA-MB-231 cells using 5-aza-2'-deoxycytidine treatment. We found that estrogen receptor-positive breast cancers were significantly more common among the methylated group than among the non-methylated group.
REIC/Dkk-3 type-a methylation was frequently detected in a broad range of cancers and appeared to play a key role in silencing REIC/Dkk-3 type-a expression in these malignancies.
Journal of Cancer Research and Clinical Oncology 01/2012; 138(5):799-809. DOI:10.1007/s00432-012-1158-6 · 3.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: REIC/Dkk-3 is a tumor suppressor gene that was first identified as a gene downregulated in association with immortalization of normal human fibroblasts. We have demonstrated that an adenovirus carrying REIC/Dkk-3 (Ad-REIC) showed a tumor-specific killing effect on a wide range of cancers. However, some human cancers, bladder cancers in particular, are resistant to Ad-REIC. In this study, we investigated the combination effect of downregulation of BRPK/PINK1 (PINK1) and Ad-REIC on bladder cancer cells. Five bladder cancer cell lines among six cell lines examined were resistant to Ad-REIC. Among the cell lines, the resistance of two cell lines was probably due to low infection efficiency of the adenovirus. PINK1-specific siRNA remarkably downregulated Bcl-xL and TRAP1 proteins and upregulated BAX protein expression. Finally, downregulation of PINK1 partially sensitized the other three cell lines that were resistant to Ad-REIC. This sensitization was associated with increasing production of reactive oxygen species (ROS). These results indicate that PINK1 is one of the key molecules for the mitochondrial protection system and that PINK1 can be a new target molecule to sensitize bladder cancer cells that are resistant to Ad-REIC.
[Show abstract][Hide abstract] ABSTRACT: S100A11, a member of the family of S100 proteins, is a dimmer, each monomer of which has two EF-hands. Expression of S100A11 is ubiquitous in various tissues at different levels, with a high expression level in the skin. We have analyzed functions of S100A11 mainly in normal human keratinocytes (NHK) as a model cell system of human epithelial cells. High Ca(2+) and transforming growth factor-β (TGF-β), two representative growth suppressors for NHK, need a common S100A11-mediated pathway in addition to unique pathways (NFAT1-mediated pathway for high Ca(2+) and Smad-mediated pathway for TGF-β) for exhibiting a growth inhibitory effect. S100A11 has another action point for growth suppression in NHK. Annexin A1 (ANXA1) complexed with S100A11 efficiently binds to and inhibits cytosolic phospholipase A2 (cPLA2), the activity of which is needed for the growth of NHK. On exposure of NHK to epidermal growth factor (EGF), ANXA1 is cleaved at 12Trp, and this truncated ANXA1 loses binding capacity to S100A11, resulting in maintenance of an active state of cPLA2. On the other hand, we found that S100A11 is actively secreted by NHK. Extracellular S100A11 acts on NHK to enhance the production of EGF family proteins, resulting in growth stimulation. These findings indicate that S100A11 plays a dual role in growth regulation, being suppressive in cells and being promotive from outside of cells.
[Show abstract][Hide abstract] ABSTRACT: REIC/Dkk-3 is a member of the Dickkopf family proteins known as Wnt-antagonists, and REIC/Dkk-3 expression is downregulated in a broad range of cancer types. REIC/Dkk-3 acts as a tumor suppressor in multiple cancer cell lines by inducing apoptosis through endoplasmic reticulum (ER) stress signaling. However, the intracellular interaction partners of REIC/Dkk-3 have not been fully elucidated. By employing yeast two-hybrid screening, we identified the human dynein light chain, Tctex-1, as a novel interaction partner of REIC/Dkk-3. We further disclosed that the interaction involves the 136-157 amino acid region of REIC/Dkk-3 by using the mammalian two-hybrid system. Interestingly, this binding region of REIC/Dkk-3 with Tctex-1 contains an amino acid sequence motif [-E-X-G-R-R-X-H-] which was previously reported as the Tctex-1 binding domain of dynein intermediate chain (DIC). Immunocytochemistry demonstrated that both REIC/Dkk-3 and Tctex-1 were localized around the ER of human fibroblasts, and the similar distribution pattern of the proteins suggests that their interaction occurs around the ER. This is the first study showing the interaction of a Dickkopf family protein with a dynein motor complex protein. The link between REIC/Dkk-3 and Tctex-1 may be of significance for understanding the molecular functions of the proteins in ER stress signaling and intracellular dynein motor dynamics, respectively.
Biochemical and Biophysical Research Communications 08/2011; 412(2):391-5. DOI:10.1016/j.bbrc.2011.07.109 · 2.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The receptor for advanced glycation end products (RAGE) is thought to be involved in the pathogenesis of a broad range of inflammatory, degenerative and hyperproliferative diseases. It binds to diverse ligands and activates multiple intracellular signaling pathways. Despite these pivotal functions, molecular events just downstream of ligand-activated RAGE have been surprisingly unknown. Here we show that the cytoplasmic domain of RAGE is phosphorylated at Ser391 by PKCζ upon binding of ligands. TIRAP and MyD88, which are known to be adaptor proteins for Toll-like receptor-2 and -4 (TLR2/4), bound to the phosphorylated RAGE and transduced a signal to downstream molecules. Blocking of the function of TIRAP and MyD88 largely abrogated intracellular signaling from ligand-activated RAGE. Our findings indicate that functional interaction between RAGE and TLRs coordinately regulates inflammation, immune response and other cellular functions.
PLoS ONE 08/2011; 6(8):e23132. DOI:10.1371/journal.pone.0023132 · 3.23 Impact Factor