Mitsuhide Noshiro

Hiroshima University, Hirosima, Hiroshima, Japan

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Publications (107)377.17 Total impact

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    ABSTRACT: Daily physiological and behavioral rhythms are regulated by endogenous circadian molecular clocks. Clock proteins DEC1 (BHLHe40) and DEC2 (BHLHe41) belong to the basic helix-loop-helix protein superfamily, which contains other clock proteins CLOCK and BMAL1. DEC1 and DEC2 are induced by CLOCK:BMAL1 heterodimer via the CACGTG E-box in the promoter and, thereafter, suppress their own expression by competing with CLOCK:BMAL1 for the DNA binding. This negative feedback DEC loop together with the PER loop involving PER and CRY, the other negative clock regulators, maintains the circadian rhythm of Dec1 and Dec2 expression. DEC1 is induced by light pulse and adjusts the circadian phase of the central clock in the suprachiasmatic nucleus, whereas DEC1 upregulation by TGF-β resets the circadian phase of the peripheral clocks in tissues. Furthermore, DEC1 and DEC2 modulate the clock output signals to control circadian rhythms in behavior and metabolism. In addition to the functions in the clocks, DEC1 and DEC2 are involved in hypoxia responses, immunological reactions, and carcinogenesis. These DEC actions are mediated by the direct binding to the E-box elements in target genes or by protein-protein interactions with transcription factors such as HIF-1α, RXRα, MyoD, and STAT. Notably, numerous growth factors, hormones, and cytokines, along with ionizing radiation and DNA-damaging agents, induce Dec1 and/or Dec2 in a tissue-specific manner. These findings suggest that DEC1 and DEC2 play a critical role in animal adaptation to various environmental stimuli.
    Current Topics in Developmental Biology 01/2014; 110C:339-372. · 6.91 Impact Factor
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    ABSTRACT: We screened circadian-regulated genes in rat cartilage by using a DNA microarray analysis. In rib growth-plate cartilage, numerous genes showed statistically significant circadian mRNA expression under both 12:12 h light-dark and constant darkness conditions. Type II collagen and aggrecan genes-along with several genes essential for post-translational modifications of collagen and aggrecan, including prolyl 4-hydroxylase 1, lysyl oxidase, lysyl oxidase-like 2, and 3'-phosphoadenosine 5'-phosphosulfate synthase 2-showed the same circadian phase. In addition, the mRNA level of SOX9, a master transcription factor for the synthesis of type II collagen and aggrecan, has a similar phase of circadian rhythms. The circadian expression of the matrix-related genes may be critical in the development and the growth of various cartilages, because similar circadian expression of the matrix-related genes was observed in hip joint cartilage. However, the circadian phase of the major matrix-related genes in the rib permanent cartilage was almost the converse of that in the rib growth-plate cartilage under light-dark conditions. We also found that half of the oscillating genes had conserved clock-regulatory elements, indicating contribution of the elements to the clock outputs. These findings suggest that the synthesis of the cartilage matrix macromolecules is controlled by cell-autonomous clocks depending upon the in vivo location of cartilage.
    Journal of Biochemistry 08/2013; · 3.07 Impact Factor
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    ABSTRACT: Several cis-acting elements play critical roles in maintaining circadian expression of clock and clock-controlled genes. Using in silico analysis, we identified 10 sequence motifs that are correlated with the circadian phases of gene expression in the cartilage. One of these motifs, an E-box-like clock-related element (EL-box; GGCACGAGGC), can mediate BMAL1/CLOCK-induced transcription, which is typically regulated through an E-box or E'-box. Expression of EL-box-containing genes, including Ank, Dbp, and Nr1d1 (Rev-erbα), was induced by BMAL1/CLOCK or BMAL1/NPAS2. Compared with the E-box, the EL-box elements had distinct responsiveness to DEC1, DEC2, and HES1: suppressive actions of DEC1 and DEC2 on the EL-box were less potent than those on the E-box. HES1, which is known to bind to the N-box (CACNAG), suppressed enhancer activity of the EL-box, but not the E-box. In the Dbp promoter, an EL-box worked cooperatively with a noncanonical (NC) E-box to mediate BMAL1/CLOCK actions. These findings suggest that in addition to known clock elements, the EL-box element may contribute to circadian regulation of clock and clock-controlled genes.
    Gene 08/2012; 510(2):118-25. · 2.20 Impact Factor
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    ABSTRACT: DEC1 (BHLHE40/Stra13/Sharp2) is a basic helix-loop-helix (bHLH) transcription factor that is involved in the regulation of apoptosis and cell proliferation and the response to hypoxia. Epithelial-mesenchymal transition (EMT) is an important step leading to invasion and migration of various tumor cells, and TGF-β treatment has been shown to induce cancer cells to undergo EMT. However, the significance of DEC1 in TGF-β-induced EMT remains unknown. We examined the role of DEC1 in EMT of PANC-1 cells, a human pancreatic cancer cell line. As a result, we found that DEC1 was upregulated by TGF-β in PANC-1 cells, and regulated the expression and the levels of nuclear, cytoplasmic or membrane localization of EMT-related factors, including phosphorylated Smad3 (pSmad3), snail, claudin-4 and N-cadherin. In the presence of TGF-β, DEC1 knockdown by siRNA inhibited morphological changes during EMT processes, while TGF-β induced PANC-1 cells to taken on a spindle-shaped morphology. Furthermore, a combination treatment of DEC1 expression with TGF-β was closely linked to the migration and invasion of PANC-1 cells. Immunohistochemically, DEC1 and pSmad3 were detected within pancreatic cancer tissues, whereas claudin-4 expression was weaker in the cancer tissues compared with the adjacent non-cancer pancreatic tissues. These findings suggest that DEC1 plays an important role in the regulation of these EMT-related factors in pancreatic cancer.
    International Journal of Oncology 07/2012; · 2.66 Impact Factor
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    ABSTRACT: The basic helix loop helix (bHLH) transcription factor DEC2 is associated with the regulation of apoptosis, circadian rhythm and the response to hypoxia. However, the significance of DEC2 in pancreatic cancer remains unknown. Here, we showed for the first time that DEC2 inhibits the progression of human pancreatic cancer. Human pancreatic cancer BxPC-3 cells were treated with or without transforming growth factor-β (TGF-β), siRNA against DEC2, or a combination of TGF-β and DEC2 siRNA or DEC2 overexpression. The cells were analyzed by RT-PCR, real-time PCR, western blotting, immunofluorescent staining and ChIP assay. We also performed immunohistochemical analyses of DEC2 expression in surgically-resected pancreatic cancers. The expression of DEC2 was increased in TGF-β-treated BxPC-3 cells. In the presence of TGF-β, DEC2 overexpression decreased the migration and invasion of BxPC-3 cells. Knockdown of DEC2 by siRNA in the presence of TGF-β significantly increased the expression and nuclear concentration of slug. We also showed that DEC2 siRNA decreased the binding of DEC2 to the E-box of the slug promoter. Immunohistochemically, little DEC2 was detected in pancreatic cancer tissues, whereas significant amounts were detected in the adjacent non-cancerous pancreatic tissues. These results indicate that DEC2 has inhibitory effects against human pancreatic cancer that involve TGF-β and slug.
    International Journal of Molecular Medicine 06/2012; 30(3):495-501. · 1.96 Impact Factor
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    ABSTRACT: Smads are intracellular signaling mediators. Complexes of Smad2 and Smad3 with Smad4 transmit transforming growth factor-beta (TGF-β) receptor-induced signaling. Snail plays important roles in mesoderm formation, gastrulation, neural crest development, and epithelial mesenchymal transition. However, it remains unknown whether Smad3 and Snail expression is circadian rhythm-dependent. Here, we showed for the first time that Smad3 and Snail show circadian expression in human gingival fibroblasts (HGF-1) and human mesenchymal stem cells (MSC) after serum shock. They also showed circadian expression in the mouse liver. We confirmed that BMAL1/2, DEC1/2, VEGF, and PER1/2/3 also show circadian expression in both HGF-1 and MSC. The mRNA peaks and phases in circadian expression of these genes differed between HGF-1 and MSC. In a luciferase assay, Smad3 promoter activity was upregulated by CLOCK/BMAL1. These findings suggest that Smad3 and Snail have circadian rhythm in vitro and vivo, and that circadian expression of Smad3 depends on CLOCK/BMAL1.
    Biochemical and Biophysical Research Communications 02/2012; 419(2):441-6. · 2.28 Impact Factor
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    ABSTRACT: DEC1 and DEC2, members of the basic helix-loop-helix superfamily, are involved in various biological phenomena including clock systems, cell differentiation and metabolism. In clock systems, Dec1 and Dec2 expression are up-regulated by the CLOCK:BMAL1 heterodimer via E-box (CACGTG), exhibiting a circadian rhythm in the suprachiasmatic nucleus (SCN), the central circadian pacemaker and other peripheral tissues. In this study, using assays of luciferase reporters, electrophoretic mobility shift and chromatin immunoprecipitation, we identified novel nuclear receptor response elements, ROR response elements (RORE), in Dec1 and Dec2 promoters. These ROREs responded to the transcriptional activator RORα, but not to the repressor REVERBα, although the Bmal1 promoter responded to both RORα and REVERBα. Therefore, RORα, but not REVERBα, is involved in the regulation of Dec1 and Dec2 expression without significantly affecting their rhythmicity. Since RORα, DEC1 and DEC2 reportedly suppressed adipogenic differentiation, we examined expression of Rorα, Dec1, Dec2 and other clock-controlled genes in differentiating 3T3-L1 adipocytes. The results suggested that RORα suppresses adipogenic differentiation at a later stage of differentiation by RORE-mediated stimulation of Dec1 and Dec2 expression.
    Genes to Cells 01/2012; 17(2):109-21. · 2.73 Impact Factor
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    ABSTRACT: DEC1 (BHLHE40/Stra13/Sharp2) and DEC2 (BHLHE41/Sharp1) are basic helix-loop-helix (bHLH) transcription factors that are involved in the regulation of apoptosis, cell proliferation, circadian rhythms and the response to hypoxia. We previously showed the functional effects of DEC1 and DEC2 on apoptosis in human breast cancer MCF-7 cells. However, the roles of DEC1 and DEC2 in oral cancer are poorly understood. We examined whether DEC1 and DEC2 are involved in the regulation of apoptosis in human oral cancer HSC-3 and CA9-22 cells. The expression of DEC2 was upregulated by cis-diamminedichloroplatinum (II) (cisplatin: CDDP) treatment in HSC-3 cells, whereas CDDP treatment had little effects on the expression of DEC2 in CA9-22 cells. We showed that DEC2 overexpression inhibits pro-apoptotic factor Bim and inhibits apoptosis induced by CDDP in HSC-3 cells, whereas it had little effects on apoptosis in CA9-22 cells. DEC1 overexpression had little effects on apoptosis induced by CDDP in these cells. We also found that CDDP upregulated the amounts of DEC2 in the nucleus in HSC-3 cells. These results suggest that DEC2 has anti-apoptotic effects on apoptosis induced by CDDP in HSC-3 cells.
    Biomedical Research 01/2012; 33(2):75-82. · 1.15 Impact Factor
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    ABSTRACT: Differentiated embryonic chondrocyte gene (DEC) 1 (BHLHE40/Stra13/Sharp2) and DEC2 (BHLHE41/Sharp1) are basic helix-loop-helix (bHLH) transcription factors that are associated with the regulation of apoptosis, cell proliferation and circadian rhythms, as well as malignancy in various cancers. However, the roles of DEC1 and DEC2 expression in breast cancer are poorly understood. In this study, we sought to examine the roles of DEC1 and DEC2 in MCF-7 human breast cancer cells that had been treated with paclitaxel. The expression of DEC1 and DEC2 was up-regulated in paclitaxel-treated MCF-7 cells. Knockdown of DEC1 by siRNA decreased the amount of cleaved poly (ADP-ribose) polymerase (PARP), after treatment with paclitaxel, whereas DEC2 knockdown increased the amount of cleaved PARP in both the presence and absence of paclitaxel. Immunofluorescent staining revealed that paclitaxel treatment increased the amount of DEC1 in the nucleus, and increased the amount of DEC2 in both the nucleus and cytoplasm. These results indicate that DEC1 has pro-apoptotic effects, whereas DEC2 has anti-apoptotic effects on the paclitaxel-induced apoptosis in human breast cancer MCF-7 cells.
    International Journal of Molecular Medicine 02/2011; 27(4):491-5. · 1.96 Impact Factor
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    ABSTRACT: DEC1 (BHLHB2/Stra13/Sharp2) and DEC2 (BHLHB3/Sharp1) are basic helix-loop-helix (bHLH) transcription factors that are involved in circadian rhythms, differentiation and the responses to hypoxia. We examined whether DEC1 and DEC2 are involved in apoptosis regulation, in human breast cancer MCF-7 cells. We found that siRNA-mediated knockdown of DEC2 resulted in marked enhancement of apoptosis compared with that in control cells transfected with nonspecific siRNA. However, knockdown of DEC1 by siRNA did not affect cell survival. Knockdown of DEC2 affected the expression of mRNA or proteins related to apoptosis, such as Fas, c-Myc, caspase-8, poly (ADP-ribose) polymerase (PARP) and Bax. We also showed that tumor necrosis factor-alpha (TNF-alpha) up-regulates the expression of DEC1 and DEC2. DEC2 over-expression caused by the transfection of an expression vector reduced the amounts of cleaved PARP and caspase-8 induced by TNF-alpha treatment, whereas DEC1 over-expression increased it. Finally, we revealed that treatment with double knockdown against both DEC1 and DEC2 decreased the amounts of cleaved PARP and caspase-8 induced by DEC2 siRNA with or without TNF-alpha. These data indicate that DEC2 has an anti-apoptotic effect, whereas DEC1 has a pro-apoptotic effect, which are involved in the balance of survival of human breast cancer MCF-7 cells.
    Genes to Cells 03/2010; 15(4):315-25. · 2.73 Impact Factor
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    ABSTRACT: The basic helix-loop-helix proteins differentiated embryo chondrocyte 1 (DEC1) and DEC2 are involved in circadian rhythm control. Because the metabolism of dietary nutrients has been linked to circadian regulation, we examined the effect of DEC1 and DEC2 on the function of the metabolite-sensing nuclear receptors, ligand-dependent transcription factors, including retinoid X receptor (RXR) and liver X receptor (LXR). Transfection assays showed that DEC1 and DEC2 repressed ligand-dependent transactivation by RXR. Knockdown of endogenous DEC1 and DEC2 expression with small interfering RNAs augmented ligand-dependent RXRalpha transactivation. DEC1 and DEC2 interacted directly with RXRalpha, and ligand addition enhanced their association. DEC1 and DEC2 modified interaction of RXRalpha with cofactor proteins. Transfection assays using DEC1 and DEC2 mutants revealed that the C-terminal region of DEC2 is required for repression and that an LXXLL motif in DEC1 and DEC2 is necessary for RXRalpha repression. DEC1 and DEC2 repressed the induction of LXR target genes, associated with the promoter of an LXR target gene, and dissociated from the promoter with ligand treatment. Knockdown of endogenous DEC1 and DEC2 enhanced the LXR target gene expression in hepatocytes. Expression of Dec1, Dec2, and Srebp-1c showed a circadian rhythm in the liver of mice, whereas that of Lxralpha, Lxrbeta, and Rxralpha was not rhythmic. DEC1 and DEC2 also repressed the transactivation of other RXR heterodimers, such as farnesoid X receptor, vitamin D receptor, and retinoic acid receptor. Thus, the repressor function of DEC1 and DEC2 may be extended to other RXR heterodimer nuclear receptors.
    Molecular pharmacology 09/2009; 76(6):1360-9. · 4.53 Impact Factor
  • Source
    Mitsuhide Noshiro
    Nippon rinsho. Japanese journal of clinical medicine 08/2009; 67(8):1454-7.
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    ABSTRACT: DEC1 (BHLHB2/Stra13/Sharp2)-a basic helix-loop-helix transcription factor-is known to be involved in various biological phenomena including clock systems and metabolism. In the clock systems, Dec1 expression is dominantly up-regulated by CLOCK : BMAL1 heterodimer, and it exhibits circadian rhythm in the suprachiasmatic nucleus (SCN)-the central circadian pacemaker-and other peripheral tissues. Recent studies have shown that the strong circadian rhythmicity of Dec1 in the SCN was abolished by Clock mutation, whereas that in the liver was affected, but not abolished, by Clock mutation. Moreover, feeding conditions affected hepatic Dec1 expression, which indicates that Dec1 expression is closely linked with the metabolic functions of the liver. Among ligand-activated nuclear receptors examined, LXRalpha and LXRbeta with T0901317-agonist for LXR-were found to be potent enhancers for Dec1 promoter activity, and a higher expression level of LXRalpha protein was detected in the liver than in the kidney and heart. T0901317 increased the levels of endogenous Dec1 transcript in hepatoma cells. Chromatin immunoprecipitation assay indicated that LXRalpha bound to the Dec1 promoter, and an LXRalpha-binding site was identified. These observations indicate that hepatic DEC1 mediates the ligand-dependent LXR signal to regulate the expression of genes involved in the hepatic clock system and metabolism.
    Genes to Cells 12/2008; 14(1):29-40. · 2.73 Impact Factor
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    ABSTRACT: DEC1 suppresses CLOCK/BMAL1-enhanced promoter activity, but its role in the circadian system of mammals remains unclear. Here we examined the effect of Dec1 overexpression or deficiency on circadian gene expression triggered with 50% serum. Overexpression of Dec1 delayed the phase of clock genes such as Dec1, Dec2, Per1, and Dbp that contain E boxes in their regulatory regions, whereas it had little effect on the circadian phase of Per2 and Cry1 carrying CACGTT E' boxes. In contrast, Dec1 deficiency advanced the phase of the E-box-containing clock genes but not that of the E'-box-containing clock genes. Accordingly, DEC1 showed strong binding and transrepression on the E box, but not on the E' box, in chromatin immunoprecipitation, electrophoretic mobility shift, and luciferase reporter assays. Dec1-/- mice showed behavioral rhythms with slightly but significantly longer circadian periods under conditions of constant darkness and faster reentrainment to a 6-h phase-advanced shift of a light-dark cycle. Knockdown of Dec2 with small interfering RNA advanced the phase of Dec1 and Dbp expression, and double knockdown of Dec1 and Dec2 had much stronger effects on the expression of the E-box-containing clock genes. These findings suggest that DEC1, along with DEC2, plays a role in the finer regulation and robustness of the molecular clock.
    Molecular and Cellular Biology 07/2008; 28(12):4080-92. · 5.04 Impact Factor
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    ABSTRACT: DEC1 (BHLHB2/Sharp2/Stra13) and DEC2 (BHLHB3/Sharp1) are basic-helix-loop-helix (bHLH) transcription factors, involved in cellular differentiation, responses to hypoxia and circadian rhythms. We recently showed that the expression of DEC1 and DEC2 was up-regulated by hypoxia; however, the functions of these two factors under hypoxic conditions have not been elucidated in detail. It is well established that the expression of vascular endothelial growth factor (VEGF) is up-regulated by hypoxia, and the expression of VEGF in response to hypoxia depends on transcriptional activation by a heterodimer comprising hypoxia-inducible factor 1alpha (HIF-1alpha) and arylhydrocarbon receptor nuclear translocator 1 (ARNT1). In the present study, we showed that DEC2, but not DEC1, suppressed VEGF gene expression under hypoxic conditions. DEC2 protein was co-immunoprecipitated with HIF-1alpha but not with ARNT1. The binding of HIF-1alpha to the hypoxia response element (HRE) in the VEGF promoter was decreased by DEC2 over-expression, and increased by DEC2 knockdown. We also showed that the circadian expression of VEGF showed a reciprocal pattern to that of DEC2 in cartilage. DEC2 had a circadian oscillation in implanted Sarcoma 180 cells. We conclude that DEC2 negatively regulates VEGF expression and plays an important role in the pathological conditions in which VEGF is involved.
    Genes to Cells 03/2008; 13(2):131-44. · 2.73 Impact Factor
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    ABSTRACT: Cholesterol 7alpha-hydroxylase (CYP7A) and sterol 12alpha-hydroxylase (CYP8B) in bile acid biosynthesis and 3-hydroxyl-3-methylglutaryl CoA reductase (HMGCR) in cholesterol biosynthesis are the key enzymes in hepatic metabolic pathways, and their transcripts exhibit circadian expression profiles in rodent liver. The authors determined transcript levels of these enzymes and the regulatory factors for Cyp7a--including Dbp, Dec2, E4bp4, Hnf4alpha, Pparalpha, Lxralpha, Rev-erbalpha, and Rev-erbbeta--in the liver of wild-type and homozygous Clock mutant mice (Clock/Clock) and examined the effects of these transcription factors on the transcription activities of Cyp7a. The expression profile of the Cyp7a transcript in wild-type mice showed a strong circadian rhythm in both the 12L:12D light-dark cycle and constant darkness, and that in Clock/Clock also exhibited a circadian rhythm at an enhanced level with a lower amplitude, although its protein level became arrhythmic at a high level. The expression profile of Cyp8b mRNA in wild-type mice showed a shifted circadian rhythm from that of Cyp7a, becoming arrhythmic in Clock/Clock at an expression level comparable to that of wild-type mice. The expression profile of Hmgcr mRNA also lost its strong circadian rhythm in Clock/Clock , showing an expression level comparable to that of wild-type mice. The expressions of Dbp, Dec2, Rev-erbalpha, and Rev-erb beta--potent regulators for Cyp7a expression--were abolished or became arrhythmic in Clock/Clock, while other regulators for Cyp7a-Lxralpha, Hnf4alpha, Pparalpha, and E4bp4--had either less affected or enhanced expression in Clock/Clock. In luciferase reporter assays, REV-ERBalpha/beta, DBP, LXRalpha, and HNF4alpha increased the promoter activity of Cyp7a, whereas DEC2 abolished the transcription from the Cyp7a promoter: E4BP4 and PPARalpha were moderate negative regulators. Furthermore, knockdown of REV-ERBalpha/beta with siRNA suppressed Cyp7a transcript levels, and in the electrophoretic mobility shift assay, REV-ERBalpha/beta bound to the promoter of Cyp7a . These observations suggest that (1) active CLOCK is essential for the robust circadian expression of hepatic metabolic enzymes (Cyp7a, Cyp8b, and Hmgcr); (2) clock-controlled genes--DBP, DEC2, and REV-ERBalpha/beta--are direct regulators required for the robust circadian rhythm of Cyp7a; and (3) the circadian rhythm of Cyp7a is regulated by multiple transcription factors, including DBP, REV-ERBalpha/beta, LXRalpha, HNF4alpha DEC2, E4BP4, and PPARalpha.
    Journal of Biological Rhythms 09/2007; 22(4):299-311. · 3.23 Impact Factor
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    ABSTRACT: Dec2, a member of the basic helix-loop-helix (bHLH) superfamily, has been shown to function as a transcriptional repressor and is implicated in cell proliferation and differentiation. In addition, Dec2 transcripts exhibit a striking circadian oscillation in the suprachiasmatic nucleus. To identify the molecular mechanisms by which Dec2 regulates gene expression, we carried out structure-function analyses. Gel retardation and luciferase assays showed that Dec2, as well as its related protein Dec1, preferentially binds to class B E-box elements (CACGTG) as a homodimer and represses the transcription of target genes in a histone deacetylase (HDAC)-dependent manner. Functional studies with the GAL4-DNA binding domain fusion proteins identified the domain responsible for the repression activity of Dec2 in its C-terminal region, which is also necessary to recruit HDAC1. In addition, the basic and HLH domains of Dec2 were required for DNA binding and homodimerization, respectively. In contrast, Dec proteins repressed a MyoD-activated promoter activity of muscle creatine kinase gene through class A E-box in an HDAC1-independent manner. Dec2 formed a heterodimer with MyoD through the basic and HLH domains. Consistent with this, both the basic and HLH domains were required for the ability of Dec2 to inhibit the transcriptional activity of MyoD. These findings indicate that Dec2 employs multiple mechanisms, including DNA-binding and protein-protein interactions, to achieve E-box-dependent transcriptional repressions.
    International Journal of Molecular Medicine 07/2007; 19(6):925-32. · 1.96 Impact Factor
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    ABSTRACT: SUMMARY • In the present study, the expression of sterol regulatory element-binding proteins (SREBPs) in livers of a novel rat model of metabolic syndrome, namely SHRSP.Z-Leprfa/IzmDmcr (SHRSP.ZF), as well as its lean littermates (SHRSP.lean), was examined. • The expression of SREBP-1c was significantly elevated in SHRSP.ZF rats, whereas expression of SREBP-2 was significantly decreased. • Serum cholesterol levels in SHRSP.ZF rats were significantly higher than those in SHRSP.lean rats. • Elevation of cholesterol levels by cholesterol loading significantly elevated SREBP-1c levels and significantly decreased SREBP-2 levels in SHRSP.lean rats, suggesting that serum cholesterol levels may be closely related to the expression SREBPs. • These results suggest that the expression of SREBP-1c and -2 is modified in the metabolic syndrome rats as a result of the high cholesterol level in these rats.
    Clinical and Experimental Pharmacology and Physiology 01/2007; 34. · 2.41 Impact Factor
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    ABSTRACT: To elucidate the food-entrainable oscillatory mechanism of peripheral clock systems, we examined the effect of fasting on circadian expression of clock genes including Dec1 and Dec2 in mice. Withholding of food for 2 days had these effects: the expression level of Dec1 mRNA decreased in all tissues examined, although Per1 mRNA level markedly increased; Per2 expression was reduced in the liver and heart only 42-46 h after the start of fasting; and expression profiles of Dec2 and Bmal1 were altered only in the heart and in the liver, respectively, whereas Rev-erbalpha mRNA levels did not change significantly. Re-feeding after 36-h starvation erased, at least in part, the effect of fasting on Dec1, Dec2, Per1, Per2, and Bmal1 within several hours, and restriction feeding shifted the phase of expression profiles of all examined clock genes including Dec1 and Dec2. These findings indicate that short-term fasting and re-feeding modulate the circadian rhythms of clock genes to different extents in peripheral tissues, and suggest that the expression of Dec1, Per1, and some other clock genes was closely linked with the metabolic activity of these tissues.
    Journal of Biochemistry 10/2006; 140(3):401-8. · 3.07 Impact Factor
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    ABSTRACT: The basic helix-loop-helix (bHLH) transcription factors, DEC2 and DEC1, play critical roles in the circadian rhythm of the suprachiasmatic nucleus (SCN). It is known that mammalian circadian rhythms are regulated by molecular clockwork systems based on a negative-feedback loop, and CLOCK/BMAL1 and CLOCK/BMAL2 enhance DEC2 transcription via CACGTG E-boxes. To understand the role of arginine 57 ((57)Arg) within the basic region of DEC2, we examined the effect of substituting this residue into DEC2 on CLOCK/BMAL2-mediated transactivation. A luciferase assay showed that substituting (57)Arg for Ala or Lys in DEC2 diminished the suppressive activity of wild-type DEC2 on CLOCK/ BMAL2-mediated transactivation, while substituting (48)Pro for Ala in DEC2 did not alter it, and the same was true for wild-type DEC2. We also showed that proteins which were wild-type and substitution mutants of DEC2 were expressed at nearly equivalent levels by Western blotting. These findings demonstrate that (57)Arg in the basic region of DEC2 is essential for its activity in suppressing CLOCK/BMAL2-mediated transactivation.
    International Journal of Molecular Medicine 07/2006; 17(6):1053-6. · 1.96 Impact Factor

Publication Stats

2k Citations
377.17 Total Impact Points

Institutions

  • 1989–2014
    • Hiroshima University
      • • Department of Dental and Medical Biochemistry
      • • Department of Biochemistry
      • • Graduate School of Science
      • • School of Dentistry
      Hirosima, Hiroshima, Japan
  • 2008
    • Hirosaki University
      Khirosaki, Aomori Prefecture, Japan
  • 2002–2005
    • Mukogawa Women's University
      • School of Pharmacy and Pharmaceutical Sciences
      Nishinomiya, Hyogo-ken, Japan
  • 1999
    • Saitama Cancer Center
      Saitama, Saitama, Japan
  • 1994–1999
    • Soka University
      • Faculty of Engineering
      Tokyo, Tokyo-to, Japan
  • 1993
    • Fukuoka University
      Hukuoka, Fukuoka, Japan