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Hiroyoshi Ariga

Publications and source records attributed to Hiroyoshi Ariga.

At least 37 records · Page 2Linked to original sources
PubMed2005

DJ-1 restores p53 transcription activity inhibited by Topors/p53BP3.

DJ-1 is a multi-functional protein that plays roles in transcriptional regulation and anti-oxidative stress, and loss of its function is thought to result in onset of Parkinson's disease. Here, we report that DJ-1 bound to Topors/p53BP3, a ring finger protein binding to both topoisomerase I and p53, in vitro and in vivo and that both proteins were colocalized in cells. DJ-1 and p53 were then found to be sumoylated by Topors in cells. It was also found that DJ-1 bound to p53 in vitro and in vivo and that colocalization with and its binding to p53 were stimulated by UV irradiation of cells. Transcription activity of p53 was found to be abrogated by Topors concomitant with sumoylation of p53 in a dose-dependent manner, and DJ-1 restored its repressed activity by releasing the sumoylated form of p53. These findings suggest that DJ-1 positively regulates p53 through Topors-mediated sumoylation.

Animals↗
PubMed2005

Stimulation of transforming activity of DJ-1 by Abstrakt, a DJ-1-binding protein.

DJ-1 was identified by us as a novel oncogene in cooperation with activated ras. Although over-expression of DJ-1 has been reported in several cancer cells, including cells in breast cancer, lung cancer and prostate cancer, the precise mechanism underlying transformation has not been clarified. In this study, we screened proteins by a yeast two-hybrid method and identified Abstrakt as a DJ-1-binding protein. Abstrakt is an RNA helicase, but it has not yet been characterized. Northern blot analysis showed that human Abstrakt was expressed ubiquitously in all tissues. Abstrakt was then found to bind to and to be colocalized in the nucleus with DJ-1 in human cells. Furthermore, Abstrakt was found to stimulate transforming activity of DJ-1 in rat 3Y1 cells transfected with DJ-1 with activated ras. These findings suggest that Abstrakt is a positive regulator for DJ-1.

Animals↗
PubMed2005

Mitochondria-independent induction of Fas-mediated apoptosis by MSSP.

Fas-mediated apoptosis has been proposed to play an important role in homeostasis. Fas triggers apoptosis after stimulation by its ligand FasL or the Fas ligand agonist anti-Fas antibody through a mitochondria-dependent or -independent pathway, and MSSP has been identified as a transcription factor that regulates the c-myc gene and was later found to positively or negatively regulate a variety of genes, including alpha-smooth actin, MHC class I, MHC class 2 and the thyrotropin receptor. We further found that expression of the Fas gene was repressed, resulting in abrogation of the Fas-mediated induction of apoptosis both in Mssp-knockout mice and primary thymocytes. MSSP was then found to stimulate promoter activity of the Fas gene by binding to a specific region. In this study, to identify the MSSP-dependent Fas-induced apoptosis pathway, primary fibroblasts from MSSP (+/+) and MSSP (-/-) cells were treated with the combination of interleukin 1-beta and interferon-gamma and expression of the Fas gene was examined. The results showed that the Fas gene was expressed at the same levels in the two cell types. Furthermore, when these cells were treated with the anti-Fas antibody, it was found that cytochrome C was not released in the cytosol and that activations of caspase 8 and caspase 3 occurred in primary fibroblasts from MSSP (+/+) cells but not from MSSP (-/-) cells. These results indicate that Fas-mediated apoptosis induced by MSSP occurs independently of mitochondria.

Animals↗
PubMed2004

CIR, a corepressor of CBF1, binds to PAP-1 and effects alternative splicing.

We have reported that PAP-1, a product of a causative gene for autosomal retinitis pigmentosa, plays a role in splicing. In this study, CIR, a protein originally identified as a CBF1-interacting protein and reported to act as a transcriptional corepressor, was identified as a PAP-1 binding protein and its function as a splicing factor was investigated. In addition to a basic lysine and acidic serine-rich (BA) domain and a zinc knuckle-like motif, CIR has an arginine/serine dipeptide repeat (RS) domain in its C terminal region. The RS domain has been reported to be present in the superfamily of SR proteins, which are involved in splicing reactions. We generated CIR mutants with deletions of each BA and RS domain and studied their subcellular localizations and interactions with PAP-1 and other SR proteins, including SC35, SF2/ASF, and U2AF35. CIR was found to interact with U2AF35 through the BA domain, with SC35 and SF2/ASF through the RS domain, and with PAP-1 outside the BA domain in vivo and in vitro. CIR was found to be colocalized with SC35 and PAP-1 in nuclear speckles. Then the effect of CIR on splicing was investigated using the E1a minigene as a reporter in HeLa cells. Ectopic expression of CIR with the E1a minigene changed the ratio of spliced isoforms of E1a that were produced by alternative selection of 5'-splice sites. These results indicate that CIR is a member of the family of SR-related proteins and that CIR plays a role in splicing regulation.

Alternative Splicing↗
PubMed2004

PAP-1, the mutated gene underlying the RP9 form of dominant retinitis pigmentosa, is a splicing factor.

PAP-1 is an in vitro phosphorylation target of the Pim-1 oncogene. Although PAP-1 binds to Pim-1, it is not a substrate for phosphorylation by Pim-1 in vivo. PAP-1 has recently been implicated as the defective gene in RP9, one type of autosomal dominant retinitis pigmentosa (adRP). However, RP9 is a rare disease and only two missense mutations have been described, so the report of a link between PAP-1 and RP9 was tentative. The precise cellular role of PAP-1 was also unknown at that time. We now report that PAP-1 localizes in nuclear speckles containing the splicing factor SC35 and interacts directly with another splicing factor, U2AF35. Furthermore, we used in vitro and in vivo splicing assays to show that PAP-1 has an activity, which alters the pattern of pre-mRNA splicing and that this activity is dependent on the phosphorylation state of PAP-1. We used the same splicing assay to examine the activities of two mutant forms of PAP-1 found in RP9 patients. The results showed that while one of the mutations, H137L, had no effect on splicing activity compared with that of wild-type PAP-1, the other, D170G, resulted in both a defect in splicing activity and a decreased proportion of phosphorylated PAP-1. The D170G mutation may therefore cause RP by altering splicing of retinal genes through a decrease in PAP-1 phosphorylation. These results demonstrate that PAP-1 has a role in pre-mRNA splicing and, given that three other splicing factors have been implicated in adRP, this finding provides compelling further evidence that PAP-1 is indeed the RP9 gene.

Annexin A5↗
PubMed2004

A novel nucleolar protein, PAPA-1, induces growth arrest as a result of cell cycle arrest at the G1 phase.

We have identified a novel nucleolar protein, PAP-1-associated protein-1 (PAPA-1), after screening the interacting proteins with Pim-1-associated protein-1 (PAP-1), a protein that is a phosphorylation target of Pim-1 kinase. PAPA-1 comprises 345 amino acids with a basic amino-acid cluster. PAPA-1 was found to be localized in the nucleolus in transfected HeLa cells, and the lysine/histidine cluster was essential for nucleolar localization of PAPA-1. PAPA-1 protein and mRNA expression decreased upon serum restimulation of starvation-synchronized cells, which displayed maximum level of PAPA-1 expression at G0 and early G1 phase of the cell cycle. Ectopic expression of PAPA-1 induced growth suppression of cells, and the effect was dependent on its nucleolar localization in established HeLa cell lines that inducibly express PAPA-1 or its deletion mutant under the control of a tetracycline-inducible promoter. Furthermore, when PAPA-1-inducible HeLa cells were synchronized by thymidine, colcemid or mimosine, and then PAPA-1 was expressed, the proportion of cells at the G1 phase was obviously increased. These results suggest that PAPA-1 induces growth and cell cycle arrests at the G1 phase of the cell cycle.

Amino Acid Sequence↗
PubMed2004

Repression of the c-fms gene in fibroblast cells by c-Myc-MM-1-TIF1beta complex.

MM-1 has been reported to repress the E-box-dependent transcription activity of c-Myc by recruiting histone deacetylase 1 complex via TIF1beta/KAP1. In this study, to identify target genes for c-Myc-MM-1-TIF1beta, we established rat-1 cells harboring the dominant-negative form of TIF1beta to abrogate the pathway from TIF1beta to MM-1-c-Myc. This cell line, in which transcription activity of c-Myc was activated, was found to be tumorigenic. By DNA-microarray analysis of this cell line, expression and promoter activity of the c-fms oncogene were found to be upregulated. Of the two promoters, pE1 and pE2, in the c-fms gene, pE1 promoter activity was found to be activated in an E-box-dependent manner.

Animals↗
PubMed2004

Modulation of collagen fibrillogenesis by tenascin-X and type VI collagen.

Tenascin-X (TNX) is an extracellular matrix glycoprotein. We previously demonstrated that TNX regulates the expression of type VI collagen. In this study, we investigated the binding of TNX to type I collagen as well as to type VI collagen and the effects of these proteins on fibrillogenesis of type I collagen. Full-length recombinant TNX, which is expressed in and purified from mammalian cell cultures, and type VI collagen purified from bovine placenta were used. Solid-phase assays revealed that TNX or type VI collagen bound to type I collagen, although TNX did not bind to type VI collagen, fibronectin, or laminin. The rate of collagen fibril formation and its quantity, measured as increased turbidity, was markedly increased by the presence of TNX, whereas type VI collagen did not increase the quantity but accelerated the rate of collagen fibril formation. Combined treatment of both had an additive effect on the rate of collagen fibril formation. Furthermore, deletion of the epidermal growth factor-like (EGF) domain or fibrinogen-like domain of TNX attenuated the initial rate of collagen fibril formation. Finally, we observed abnormally large collagen fibrils by electron microscopy in the skin from TNX-deficient (TNX-/-) mice during development. These findings demonstrate a fundamental role for TNX and type VI collagen in regulation of collagen fibrillogenesis in vivo and in vitro.

Animals↗
PubMed2004

Reduced anti-oxidative stress activities of DJ-1 mutants found in Parkinson's disease patients.

DJ-1 is a multi-functional protein that plays roles in transcriptional regulation and anti-oxidative stress, and loss of its function is thought to result in onset of Parkinson's disease. We have previously reported that L166P, a mutant DJ-1 found in Parkinson's disease patients, had no activity to prevent hydrogen peroxide (H2O2)-induced cell death. In this study, we analyzed other mutants of DJ-1 found in Parkinson's disease patients, including M26I, R98Q, and D149A, as well as L166P. We first found that all of the mutants made heterodimers with wild-type DJ-1, while all of the mutants except for L166P made homodimers. We then found that M26I and L166P, both of which are derived from homozygous mutations of the DJ-1 gene, were unstable and that their stabilities were recovered, in part, in the presence of proteasome inhibitor, MG132. NIH3T3 cell lines stably expressing these mutants of DJ-1 showed that cell lines of L166P and C106S, a mutant for protease activity (-) of DJ-1, had no activity to scavenge even endogenously producing reactive oxygen species. These cell lines also showed that all of the mutants had reduced activities to eliminate exogenously added H2O2 and that these activities, except for that of D149A, were parallel to those preventing H2O2-induced cell death.

3T3 Cells↗
PubMed2004

Induction of matrix metalloproteinase-2 by tenascin-X deficiency is mediated through the c-Jun N-terminal kinase and protein tyrosine kinase phosphorylation pathway.

The results of our previous study showed that tumor invasion and metastasis are promoted in extracellular matrix (ECM) tenascin-X-deficient (TNX-/-) mice via increased expression of matrix metalloproteinases (MMPs). However, little is known about the relationship between TNX deficiency and activation of MMP genes. In this study, we investigated the molecular mechanism by which TNX deficiency activates the MMP-2 gene. We examined the intracellular signaling pathways that regulate gene expression of the proteinase in isolated fibroblasts. Results of gelatin zymography showed that MMP-2 was induced to a greater extent in TNX-/- fibroblasts embedded in type I collagen than in wild-type fibroblasts. RT-PCR analysis revealed that the increased level of MMP-2 expression was caused at the transcription level. Conversely, stable overexpression of TNX in a fibroblast cell line reduced MMP-2 expression and suppressed MMP-2 promoter activity. In addition, treatment of TNX-/- fibroblasts with SP600125, a c-Jun N-terminal kinase (JNK) inhibitor, and genistein, a tyrosine kinase inhibitor, suppressed the increased level of proMMP-2 and increased MMP-2 promoter activity in TNX-/- fibroblasts. Furthermore, increased activation of JNK and tyrosine phosphorylation of certain proteins were observed in TNX-/- fibroblasts. These findings suggest that induction of MMP-2 by TNX deficiency is mediated, at least in part, through the JNK and protein tyrosine kinase phosphorylation pathway.

Androstadienes↗
PubMed2004

Deficiency of tenascin-X causes a decrease in the level of expression of type VI collagen.

Tenascin-X (TNX) is an extracellular matrix glycoprotein. We previously demonstrated that TNX-null fibroblasts exhibit decreased cell-matrix and cell-cell adhesion. In this study, we used a differential display technique to determine the genes involved in this process. Differential display analysis of wild-type and TNX-null fibroblasts revealed that mRNA expression level of type VI collagen alpha3 is predominantly decreased in TNX-null fibroblasts. Expression levels of mRNAs of other subunits of type VI collagen, alpha2 and alpha3 chains, were also remarkably decreased in TNX-null fibroblasts. The protein level of alpha3 chain of type VI collagen was also reduced in TNX-null fibroblasts. However, the organization of type VI collagen in the extracellular matrix of TNX-null fibroblasts was similar to that of wild-type fibroblasts. Transient expression of TNX in Balb3T3 cells caused an increase in the level of mRNA of type VI collagen compared with that in vector control and increased the promoter activity of type VI collagen alpha1 subunit gene. In addition, the expression levels of type I collagen and other collagen fibril-associated molecules such as type XII and type XIV collagens, decorin, lumican and fibromodulin in wild-type and TNX-null fibroblasts were compared. It was found that the mRNA expression levels of type I collagen and collagen fibril-associated molecules other than decorin were decreased and that the expression level of decorin was increased in TNX-null fibroblasts. The results suggest the possibility that TNX mediates not only cell-cell and cell-matrix interactions but also fibrillogenesis via collagen fibril-associated molecules.

Animals↗
PubMed2004

Cysteine-106 of DJ-1 is the most sensitive cysteine residue to hydrogen peroxide-mediated oxidation in vivo in human umbilical vein endothelial cells.

Mutation in DJ-1 gene is the cause of autosomal recessive Parkinson's disease, however, its physiological function remains unclear. The isoelectric point of DJ-1 shows an acidic shift after cells are treated with hydrogen peroxide. This suggests that DJ-1 is modified in response to oxidative stress. Here we report the structural characterization of an acidic isoform of DJ-1 using a proteomic approach with nanospray interface liquid chromatography-electrospray ionization/linear ion trap mass spectrometer. When human umbilical vein endothelial cells were exposed to hydrogen peroxide, all three cysteines in DJ-1 were oxidized to cysteine sulphonic acid. Although a small part of the Cys-46 and Cys-53 were oxidized, Cys-106 was oxidized completely at any hydrogen peroxide concentration used here. These results suggest that Cys-106 is the most sensitive among three cysteine residues to oxidative stress, and that DJ-1 function is regulated, in terms of the intracellular redox state, by oxidation of Cys-106.

Amino Acid Sequence↗
PubMed2004

DJ-1 has a role in antioxidative stress to prevent cell death.

Deletion and point (L166P) mutations of DJ-1 have recently been shown to be responsible for the onset of familial Parkinson's disease (PD, PARK7). The aim of this study was to determine the role of DJ-1 in PD. We first found that DJ-1 eliminated hydrogen peroxide in vitro by oxidizing itself. We then found that DJ-1 knockdown by short interfering RNA rendered SH-SY5Y neuroblastoma cells susceptible to hydrogen peroxide-, MPP+- or 6-hydroxydopamine-induced cell death and that cells harbouring mutant forms of DJ-1, including L166P, became susceptible to death in parallel with the loss of oxidized forms of DJ-1. These results clearly showed that DJ-1 has a role in the antioxidative stress reaction and that mutations of DJ-1 lead to cell death, which is observed in PD.

Animals↗
PubMed2004

Triglyceride accumulation and altered composition of triglyceride-associated fatty acids in the skin of tenascin-X-deficient mice.

Tenascin-X (TNX) is a member of the tenascin family of glycoproteins of the extracellular matrix. Here, we observed abnormalities in the skin of TNX-deficient mice in comparison with that of wild-type mice. Histological analysis with Oil Red O staining demonstrated that there was considerable accumulation of lipid in the skin of TNX-deficient (TNX-/-) mice. By thin-layer chromatography of total lipids, it was found that the level of triglyceride was significantly increased in TNX-/- mice. The mRNA levels of most of the lipogenic enzyme genes examined were remarkably increased in TNX-/- mice. By gas chromatography-mass spectrometry analysis of triglyceride-associated fatty acids in the skin, saturated fatty acid palmitoic acid was decreased, whereas unsaturated fatty acids palmitoleic acid and oleic acid were increased in TNX-/- mice compared with those in wild-type mice. Conversely, fibroblast cell lines transfected with TNX showed a significant decrease in the amount of triglyceride. An increase in the saturated fatty acid stearic acid and decreases in the unsaturated fatty acids palmitoleic acid, oleic acid and linoleic acid, compared to those in mock-transfected cells were also caused by over-expression of TNX. These results indicate that TNX is involved in the regulation of triglyceride synthesis and the regulation of composition of triglyceride-associated fatty acids.

Adipose Tissue↗
PubMed2004

Comparison of the compositions of phospholipid-associated fatty acids in wild-type and extracellular matrix tenascin-X-deficient mice.

Tenascin-X (TNX) is a member of the tenascin family of glycoproteins of the extracellular matrix. We previously showed that TNX regulates the synthesis of triglyceride and the composition of triglyceride-associated fatty acids. The aim of the present study was to determine whether TNX controls the synthesis of phospholipids and the composition of phospholipid-associated fatty acids by using TNX-deficient (TNX-/-) mice and TNX-overexpressing fibroblast cell lines. Thin-layer chromatography of total lipids of the skin and sciatic nerves from wild-type and TNX-/- mice revealed that the amounts of major phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), in wild-type and TNX-/- mice are not different. Gas chromatography-mass spectrometry showed that the major fatty acid compositions of PC and PE in wild-type and TNX-/- mice are almost the same. Fibroblast cells stably overexpressing TNX also showed almost the same amounts of PC and PE and almost the same fatty acid compositions of PC and PE as those in mock-transfected cells. These results suggest that TNX regulates the amount of triglyceride and the composition of triglyceride-associated fatty acids but not the amount and species of phospholipids or the composition of phospholipid-associated fatty acids.

Animals↗
PubMed2004

Co-localization with DJ-1 is essential for the androgen receptor to exert its transcription activity that has been impaired by androgen antagonists.

DJ-1 was first identified as a novel candidate of an oncogene product in cooperation with an activated ras, and DJ-1 was later found to be a positive regulator of the androgen receptor (AR) transcription activity that was repressed by PIASxalpha. DJ-1 was also found to be an infertility-related protein that was reduced in rat sperm treated with sperm toxicants that cause infertility in rats. To determine the roles of DJ-1 in the AR function, the effects of several androgen antagonists, some of which had been identified as endocrine-disrupting chemicals, on AR transcription activity and localization of AR and DJ-1 in Cos7 cells were examined. Co-localization of DJ-1 with the AR as dot-like spots in the nucleus was first found in cells that had not been treated with chemicals. Although all of the chemicals tested inhibited AR transcription activity to an average of 25% of that without chemicals, there were two classes affecting the localization of the two proteins; one changes the AR from dot-like spots to diffuse spaces in the nucleus and the other still keeps the AR in the dot-like spots. The localization of DJ-1, on the other hand, was found to be dramatically changed by all of the chemicals, resulting in loss of co-localization with the AR. These results indicate that DJ-1 is an essential factor for the AR to exert its full activity.

Androgen Antagonists↗
PubMed2003

Down regulation of DJ-1 enhances cell death by oxidative stress, ER stress, and proteasome inhibition.

Mutations in DJ-1 gene have been linked to autosomal recessive early onset parkinsonism (AR-EOP). Although the mechanism of neuronal cell death due to DJ-1 mutation has not been fully elucidated, loss of DJ-1 function was considered to cause the phenotype. Here, we demonstrated that the down regulation of endogenous DJ-1 of the neuronal cell line by siRNA enhanced the cell death which was induced by oxidative stress, ER stress, and proteasome inhibition, but not by pro-apoptotic stimulus. The cell death with hydrogen peroxide was dramatically rescued by over-expression of wild-type DJ-1, but not by that of L166P mutant DJ-1. Furthermore, DJ-1 rescued the cell death caused by over-expression of Pael receptor, which was a substrate of Parkin, another gene product for autosomal recessive juvenile parkinsonism. These results suggest that loss of protective activity of DJ-1 from neuro-toxicity induced by these stresses contributes to neuronal cell death in AR-EOP with mutant DJ-1.

Animals↗