[Show abstract][Hide abstract] ABSTRACT: Carnosine, a histidine-containing dipeptide, is well known to be associated with skeletal muscle performance. However, there is limited information on the effect of dietary micronutrients on muscle carnosine level. Pyridoxal 5′-phosphate (PLP), the active form of vitamin B6, is involved in amino acid metabolisms in the body as a co-factor. We hypothesized that enzymes involved in β-alanine biosynthesis, the rate-limiting precursor of carnosine, may also be PLP-dependent. Thus, we examined the effects of dietary vitamin B6 on the muscle carnosine content of rats. Male and female rats were fed a diet containing 1, 7, or 35 mg pyridoxine HCl/kg for 6 weeks. Carnosine in skeletal muscles was quantified by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). In the gastrocnemius muscle of male rats, carnosine concentration was significantly higher in the 7 and 35 mg groups (+70% and +61%, respectively) than in the 1 mg pyridoxine HCl/kg group, whereas that in the soleus muscle of male rats was significantly higher only in the 7 mg group (+43%) than in the 1 mg pyridoxine HCl/kg group (P
[Show abstract][Hide abstract] ABSTRACT: This study was performed to examine the effect of dietary level of vitamin B6 on the concentrations of carnosine and anserine, antioxidants, in the heart of rats. Analysis using UPLC-MS/MS showed that the concentrations of these dipeptides in the 7 and 35 mg pyridoxine HCl/kg groups were significantly higher than those in the 1 mg pyridoxine HCl/kg group, implying the novel role of dietary vitamin B6 as a determinant of the dipeptides favorable for heart.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to examine whether prolonged low-frequency force depression (PLFFD) that occurs in situ is the result of decreased myofibrillar Ca(2+) sensitivity and/or reduced sarcoplasmic reticulum (SR) Ca(2+) release. Intact rat gastrocnemius muscles were electrically stimulated via the sciatic nerve until force was reduced to ~50 % of the initial and dissected 30 min following the cessation of stimulation. Skinned fibre and whole muscle analyses were performed in the superficial region composed exclusively of type IIB fibres. Fatiguing stimulation significantly reduced the ratio of force at low frequency to that at high frequency to 65 % in skinned fibres (1 vs. 50 Hz) and 73 % in whole muscles (20 vs. 100 Hz). In order to evaluate changes in myofibrillar Ca(2+) sensitivity and ryanodine receptor caffeine sensitivity, skinned fibres were activated in Ca(2+)- and caffeine-containing solutions, respectively. Skinned fibres from fatigued muscles displayed decreased caffeine sensitivity together with increased myofibrillar Ca(2+) sensitivity. Treatment with 2,2'-dithiodipyridine and reduced glutathione induced a smaller increase in myofibrillar Ca(2+)sensitivity in fatigued than in rested fibres. In fatigued muscles, S-glutathionylation of troponin I was increased and submaximal SR Ca(2+) release, induced by 4-chloro-m-cresol, was decreased. These findings suggest that in the early stage of PLFFD that occurs in fast-twitch muscles of exercising animals and humans, S-glutathionylation of troponin I may attenuate PLFFD by increasing myofibrillar Ca(2+) sensitivity and that under such a circumstance, PLFFD may be ascribable to failure of SR Ca(2+) release.
No preview · Article · Feb 2015 · Journal of Muscle Research and Cell Motility
[Show abstract][Hide abstract] ABSTRACT: Macrophage infiltration in the adipose tissue, and the interaction with adipocytes, is well documented to be involved in fat inflammation and obesity-associated complications. In this study, we isolated IκB kinase ε (IKKε) as a key adipocyte factor that is potentially affected by interaction with macrophages in adipose tissue in vivo. We showed that IKKε mRNA expression levels in white adipose tissue were increased in both genetic and diet-induced obese mouse. Furthermore, IKKε mRNA expression was decreased by the administration of vitamin B6, an anti-inflammatory vitamin, and that IKKε expression levels in adipose tissue were closely correlated with the numbers of infiltrating macrophages. In a co-culture system, we showed that IKKε expression in adipocytes was upregulated by interaction with activated macrophages. This study provides novel insight into IKKε, which is involved in adipose tissue inflammation during the development of obesity.
No preview · Article · Aug 2014 · Bioscience Biotechnology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: This study demonstrated 0.5% dietary rutin, ellagic acid, or curcumin markedly increased cecal succinate levels in rats fed a high-fat diet, while catechin, caffeic acid, and quercetin did not. Other organic acids were modestly or hardly affected by polyphenols. To clarify the effects of succinate levels increased by polyphenols, we examined the effects of succinate on the growth and proliferation of colon cancer cells and angiogenesis. The growth and proliferation of HT29 human colon cancer cells and angiogenesis in an ex vivo model were significantly inhibited by succinate at a dose close to that in the cecum of rats fed polyphenols. Furthermore, succinate inhibited the migration of human umbilical vein endothelial cells. These findings suggest that consumption of some polyphenols affect the health and diseases of the large intestine by elevating succinate.
No preview · Article · May 2014 · Journal of Agricultural and Food Chemistry
[Show abstract][Hide abstract] ABSTRACT: Increasing evidence indicates vitamin B6 acts as a protective factor against colon cancer. However, the mechanisms of the effect of vitamin B6 are poorly understood. The present preliminary study using DNA microarray and real-time PCR indicates p21 mRNA is upregulated in human colon carcinoma (HT29) cells exposed to pyridoxal (PL, 500 µM). A similar effect was observed in human epithelial colorectal adenocarcinoma (Caco2) cells, human colon adenocarcinoma (LoVo) cells, human embryonic kidney (HEK293T) cells, and human hepatoma (HepG2) cells. Adding other B6-vitamers such as pyridoxal 5'-phosphate (PLP), pyridoxine (PN), and pyridoxamine (PM) caused no such effect. In order to understand the mechanism of higher mRNA expression of p21 by PL, effect of PL on the p53 activation was examined (the upstream factor for p21 mRNA transcription) in HT29 cells, LoVo cells, and HepG2 cells. PL increased the phosphorylated p53 protein levels (active form) in whole-cell lysates and the nuclei of the cells. Noteworthy, the consumption of a vitamin B6-deficient diet for 5 weeks significantly reduced p21 mRNA levels and tended to reduce phosphorylated p53 protein levels (P=0.053) in the colons of mice compared to a diet with adequate vitamin B6. Thus, these results suggest vitamin B6 plays a role in increasing p21 gene expression via p53 activation in several cancer cells and the mouse colon.
[Show abstract][Hide abstract] ABSTRACT: The present study investigated changes in autolysis of three calpain isoforms in skeletal muscles undergoing eccentric contractions (ECC), leading to prolonged force deficits. Rat extensor digitorum longus and tibialis anterior muscles were exposed to 200-repeated ECC in situ, excised immediately after or 3 or 6 days after cessation of ECC, and used for measures of force output and for biochemical analyses. Full restoration of tetanic force in ECC-treated muscles was not attained until 6 days of recovery. Maximal calpain activity determined by a fluorogenic substrate was unaltered immediately after ECC, but increased to 313 and 450 % after 3 and 6 days, respectively. Increases in the amount of autolyzed calpain-3 were apparent immediately and developed progressively with recovery time, whereas elevations of autolyzed μ- and m-calpain occurred after 3 and 6 days, respectively. The protein content was augmented only in m-calpain. It is suggested that the three calpain isoforms may be involved in the dismantling, repair, remodeling and/or regeneration processes in ECC-treated muscles.
No preview · Article · Feb 2014 · Journal of Muscle Research and Cell Motility
[Show abstract][Hide abstract] ABSTRACT: The glycerophosphodiester phosphodiesterases are evolutionarily conserved proteins that have been linked to several patho/ physiological functions, comprising bacterial pathogenicity and mammalian cell proliferation or differentiation. The bacterial enzymes do not show preferential substrate selectivities among the glycerophosphodiesters, and they are mainly dedicated to glycerophosphodiester hydrolysis, to produce glycerophosphate and alcohols, as the building blocks that are required for bacterial biosynthetic pathways. In some cases, this enzymatic activity has been demonstrated to contribute to bacterial pathogenicity, as with Hemophilus influenzae. Mammalian glyerophosphodiesterases have high substrate specificities even if the number of potential physiological substrates is continuously increasing. Some of these human enzymes have been directly linked to cell differentiation, as for GDE2, which triggers motor neuron differentiation, and for GDE3, the enzymatic activity of which is necessary and sufficient to induce osteoblast differentiation. Instead, GDE5 has been shown to inhibit skeletal muscle development independent of its enzymatic activity. This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Increasing evidence suggests that dietary vitamin B6 is linked to the prevention of cancer and cardiovascular disease. However, the molecular mechanisms involved in this process are not yet understood. Preliminary results in the current study indicated, following DNA microarray analysis and quantitative PCR, that insulin‑like growth factor‑binding protein 1 (IGFBP1) mRNA is upregulated in HT29 colon carcinoma cells exposed to pyridoxal (PL, 500 µM). IGFBP1 is secreted from the liver and is hypothesized to exert a protective role in the development of cancer and cardiovascular disease. Thus, further experiments were performed to investigate the effect of PL on the expression of IGFBP1 in HepG2 hepatocellular carcinoma cells. The addition of PL (500 µM) markedly increased the expression of IGFBP1 mRNA in HepG2 cells at 6, 12 and 24 h (P<0.01), whereas other vitamers (500 µM), including pyridoxal 5'‑phosphate (PLP), pyridoxine (PN) and pyridoxamine (PM), caused no such effect. The expression of the IGFBP1 protein in the cell lysate and culture medium was elevated in the presence of PL. PL elevated expression of the active form of ERK1 protein, p‑ERK1, and the p‑c‑Jun protein, a downstream factor of ERK. Furthermore, IGFBP1 expression, elevated by PL, was suppressed by PD98059, an ERK inhibitor. Higher expression of IGFBP1 protein by PL was suppressed by cycloheximide. These results suggest that PL may induce the expression of IGFBP1 in hepatoma cells via a mechanism involving the ERK/c‑Jun pathway.
Preview · Article · Aug 2013 · Molecular Medicine Reports
[Show abstract][Hide abstract] ABSTRACT: Macrophage infiltration into adipose tissue is associated with obesity and the crosstalk between adipocytes and infiltrated macrophages has been investigated as an important pathological phenomenon during adipose tissue inflammation. Here, we sought to identify adipocyte mRNAs that are regulated by interaction with infiltrated macrophages in vivo. An anti-inflammatory vitamin, vitamin B6, suppressed macrophage infiltration into white adipose tissue and altered mRNA expression. We identified >3500 genes whose expression is significantly altered during the development of obesity in db/db mice, and compared them to the adipose tissue mRNA expression profile of mice supplemented with vitamin B6. We identified PTX3 and MMP3 as candidate genes regulated by macrophage infiltration. PTX3 and MMP3 mRNA expression in 3T3-L1 adipocytes was up-regulated by activated RAW264.7 cells and these mRNA levels were positively correlated with macrophage number in adipose tissue in vivo. Next, we screened adipose genes down-regulated by the interaction with macrophages, and isolated RASSF6 (Ras association domain family 6). RASSF6 mRNA in adipocytes was decreased by culture medium conditioned by activated RAW264.7 cells, and RASSF6 mRNA level was negatively correlated with macrophage number in adipose tissue, suggesting that adipocyte RASSF6 mRNA expression is down-regulated by infiltrated macrophages in vivo. Finally, this study also showed that decreased RASSF6 expression up-regulates mRNA expression of several genes, such as CD44 and high mobility group protein HMGA2. These data provide novel insights into the biological significance of interactions between adipocytes and macrophages in adipose tissue during the development of obesity.
[Show abstract][Hide abstract] ABSTRACT: To examine the responses of the levels of B(6)-vitamers in several tissues to the dietary level of pyridoxine (PN), mice were fed diets containing 0, 1, 7 (the recommended level) or 35 mg PN HCl/kg diet for 5 wk. Compared with the 0 mg PN HCl/kg diet, the 35 mg PN HCl/kg diet caused the highest elevation in the concentration of pyridoxal 5'-phosphate (PLP) in small intestine and epididymal adipose tissue, moderate elevation in colon, lung, spleen and stomach, slight elevation in brain, kidney and liver (p<0.05), and no elevation in heart and gastrocnemius muscle. In general, the alterations in PLP level in many tissues and serum were remarkable for diets between 1 mg and 7 mg PN HCl/kg diets. Compared to the 7 mg PN HCl/kg diet, the 35 mg PN HCl/kg diet further elevated the PLP level in adipose tissue, spleen and stomach (p<0.05). Dietary supplemental PN elevated the level of PN in small intestine and colon in a dose-dependent manner (p<0.05), but not in other tissues. There was a significant correlation between the PN and PLP levels in small intestine and colon (p<0.05), implying that PN absorbed from the diet can be at least in part metabolized to PLP within the absorptive intestinal cells. The results suggest that the responses of concentrations of B(6)-vitamers to dietary level of PN greatly differ among several tissues.
Full-text · Article · Dec 2012 · Journal of Nutritional Science and Vitaminology
[Show abstract][Hide abstract] ABSTRACT: To examine the effect of supplemental dietary vitamin B(6) on the colonic luminal environment, growing male rats were fed a high-fat diet containing 1, 7, or 35 mg pyridoxine HCl/kg diet for 6 wk. Food intake and growth were unaffected by the dietary treatment. Supplemental dietary vitamin B(6) significantly reduced the production of a fecal secondary bile acid, lithocholic acid (the most toxic secondary bile acid and a risk factor for colon cancer), and markedly reduced the ratio of lithocholic acid to deoxycholic acid (a less toxic secondary bile acid) in feces (p<0.05). Increasing dietary vitamin B(6) increased fecal mucin levels (a marker of intestinal barrier function) in a dose-dependent manner (p<0.05) but did not affect fecal immunoglobulin A levels (an index of intestinal immune function). Cecal levels of organic acids were not significantly affected by supplemental dietary vitamin B(6). These results suggest the possibility that dietary vitamin B(6) affects the colonic luminal environment by altering the production of secondary bile acids and mucins.
No preview · Article · Oct 2012 · Journal of Nutritional Science and Vitaminology
[Show abstract][Hide abstract] ABSTRACT: Previous studies have shown that vitamin B6 supplementation suppresses the development of colonic aberrant crypt foci (ACF), precursor lesions of colon cancer, and cell proliferation in mice receiving the colonic carcinogen, azoxymethane (AOM). This study investigated the molecular mechanism of these effects of dietary vitamin B6.
To date, the mechanism by which ACFs develop is not yet fully understood. In a search for factors that play a critical role during ACF development, we examined colon gene expression during early stage of ACF development in AOM-treated mice using DNA microarray analysis. AOM treatment significantly upregulated mRNA closely related to mast cell and cytotoxic T-cell activity. This study also investigated the effect of vitamin B6 supplementation on colon gene expression in AOM-treated mice. We found that vitamin B6 supplementation downregulates Cd8a and Ccl8 mRNA expression, suggesting these candidate genes may play a protective role against colonic ACF development. Furthermore, we examined genomic affects of dietary vitamin B6, and showed that Reg3γ mRNA expression in colons is downregulated by vitamin B6.
This study provides an insight into the genomic activities of dietary vitamin B6 that may be protective against colon tumor development.
No preview · Article · Apr 2012 · Molecular Nutrition & Food Research
[Show abstract][Hide abstract] ABSTRACT: Mounting evidence indicates that vitamin B6 is a protective factor for colon cancer. Elevations in colonic damage, cell proliferation and heat shock proteins (HSPs, molecular chaperones) have been suggested to be associated with colon carcinogenesis. This study was performed to examine the effect of dietary levels of vitamin B6 (1, 7 or 35 mg pyridoxine HCl/kg diet) for 22 weeks on colon damage, epithelial cell proliferation and expression of HSPs in rats exposed to 1,2-dimethylhydrazine (DMH). Supplemental vitamin B6 with a low vitamin B6 diet (1 mg pyridoxine HCl/kg diet) significantly reduced fecal activity of intestinal alkaline phosphatase (an index of intestinal damage) and the colonic epithelium PCNA labeling index (a marker of cell proliferation). Analysis using ELISA indicated that supplemental vitamin B6 significantly lowered protein levels of colonic HSP70 and heme oxygenase-1, HSP32 (HO-1). However, real-time RT-PCR analysis revealed that the mRNA levels of these HSPs were not decreased by supplemental vitamin B6, suggesting that the lowering effect of vitamin B6 on the colon protein expression of the HSPs is mediated by mechanisms not involving altered gene expression. This study provided evidence that dietary supplemental vitamin B6 suppresses colon damage, epithelial cell proliferation and protein expression of HSP70 and HO-1, the targets for anti-tumor agents, in rats exposed to DMH.
[Show abstract][Hide abstract] ABSTRACT: In this study, we investigated the effect of fish oil on gene expression in the cerebral cortex, and found that 5-aminolevulinate synthase 2 (ALAS2) mRNA expression was up-regulated by fish oil feeding. ALAS2 promoter activity was found to be regulated by retinoic acid. Our results suggest that fish oil modulates neuronal functions via heme synthesis.
No preview · Article · Jul 2011 · Bioscience Biotechnology and Biochemistry
[Show abstract][Hide abstract] ABSTRACT: We previously demonstrated that vitamin B6 suppresses tumorigenesis in the colon of mice and exerts an anti-inflammatory effect through the inhibition of NF-κB activation. As these effects resemble the pharmacological properties of thiazolidinedione (TZD), a synthetic peroxisome proliferator-activated receptor-γ (PPARγ) ligand, this study was designed to examine the effect of vitamin B6 on the activation of PPARγ and adipogenesis in 3T3-L1 adipocyte cells. Pyridoxal 5'-phosphate (PLP), one of the vitamin B6 derivatives, was shown to promote adipogenesis in the 3T3-L1 adipocytes. In addition, PLP specifically induced mRNA expression of PPARγ target genes in the 3T3-L1 adipocytes and enhanced the lipid accumulation and adipocyte fatty acid-binding protein (aP2) mRNA expression in NIH3T3 cells stably expressing PPARγ. Furthermore, the administration of vitamin B6 increased the expression of aP2 mRNA in mouse adipose tissues. Collectively, these observations suggest a novel function of vitamin B6 as an activator for PPARγ, which may contribute to the anti-tumor and anti-inflammatory effects of vitamin B6.
No preview · Article · May 2011 · Experimental and therapeutic medicine
[Show abstract][Hide abstract] ABSTRACT: Previous reports in the areas of animal studies and, recently epidemiology, have linked anti-tumorigenic and anti-inflammatory effects to dietary vitamin B6. This study investigated the molecular mechanism of these effects of vitamin B6.
DNA microarray analysis was used to obtain information on changes in colon gene expression from vitamin B6 (pyridoxine) repletion in vitamin B6-deficient rats. Pyridoxine supplementation down-regulated the inflammatory molecule, serine protease inhibitor clade A member 3 (SPI-3) mRNA expression in the colon. This study also showed that tumor necrosis factor α (TNF-α) induced SPI-3 mRNA expression in HT-29 human colon cancer cells, and vitamin B6 (pyridoxal hydrochloride) pretreatment of HT-29 cells inhibited TNF -induced mRNA expression of SPI-3. Vitamin B6 inhibited TNF-α-induced NF-κB activation via suppression of IκBα degradation in HT-29 cells. HT-29 cells stably expressing epitope-tagged ubiquitin were generated and vitamin B6 pretreatment was shown to inhibit ubiquitination of the IkB protein in response to TNF-α-i.
Vitamin B6 suppressed SPI-3 expression in the colon of rats and in TNF-α-stimulated HT-29 cells. Further, this study showed a possible role of vitamin B6 in the regulation of protein ubiquitination.
No preview · Article · Apr 2011 · Molecular Nutrition & Food Research
[Show abstract][Hide abstract] ABSTRACT: The present study investigated the effects of eccentric muscle contractions (ECC) on the content of myofibrillar proteins (my-proteins) and the catalytic activity of myofibrillar ATPase (my-ATPase) in skeletal muscles. Rat extensor digitorum longus and tibialis anterior muscles were exposed to 200-repeated ECC or isometric contractions (ISC) and used for measures of force output and for biochemical analyses, respectively. Whereas in ISC-treated muscles, full restoration of tetanic force was attained after 2 days of recovery, force developed by ECC-treated muscles remained depressed (P < 0.05) after 6 days. The total my-protein content and the relative content of myosin heavy chain (MHC) in total my-proteins were unaltered during 4 days of recovery after ECC, but fell (P < 0.05) to 55.9 and 63.4% after 6 days of recovery, respectively. my-ATPase activity expressed on a my-protein weight basis was unaltered immediately after ECC. However, it decreased (P < 0.05) to 75.3, 45.3, and 49.3% after 2, 4 and 6 days of recovery, respectively. Total maximal calpain activity measured at 5 mM Ca(2+) was significantly augmented (P < 0.05) after 2 days of recovery, reaching a level of threefold higher after 6 days. These alterations were specific for ECC and not observed for ISC. These results suggest that depressions in my-ATPase activity contribute to ECC-induced decreases in force and power which can take a number of days to recover.
No preview · Article · Nov 2010 · Arbeitsphysiologie
[Show abstract][Hide abstract] ABSTRACT: Mammalian glycerophosphodiester phosphodiesterases (GP-PDEs) have been identified recently and shown to be implicated in several
physiological functions. This study isolated a novel GP-PDE, GDE5, and showed that GDE5 selectively hydrolyzes glycerophosphocholine
(GroPCho) and controls skeletal muscle development. We show that GDE5 expression was reduced in atrophied skeletal muscles
in mice and that decreasing GDE5 abundance promoted myoblastic differentiation, suggesting that decreased GDE5 expression
has a counter-regulatory effect on the progression of skeletal muscle atrophy. Forced expression of full-length GDE5 in cultured
myoblasts suppressed myogenic differentiation. Unexpectedly, a truncated GDE5 construct (GDE5ΔC471), which contained a GP-PDE
sequence identified in other GP-PDEs but lacked GroPCho phosphodiesterase activity, showed a similar inhibitory effect. Furthermore,
transgenic mice specifically expressing GDE5ΔC471 in skeletal muscle showed less skeletal muscle mass, especially type II
fiber-rich muscle. These results indicate that GDE5 negatively regulates skeletal muscle development even without GroPCho
phosphodiesterase activity, providing novel insight into the biological significance of mammalian GP-PDE function in a non-enzymatic