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Tokushima-shi, Japan

Morita K.,Shikoku University | Lee M.-S.,Korea Basic Science Institute | Her S.,Korea Basic Science Institute | Nishibori N.,Shikoku Junior College
Cell Biology International | Year: 2014

Polyamines are widely distributed in living organisms, and considered to play a potential role in various cellular processes. The effects of polyamines on gene expression as well as cell proliferation have been suggested to be closely associated with the physiological and pathological functions. However, it seems necessary to investigate their potential roles in the regulation of cellular metabolism and functions. Previously, glial cells have been suggested to be involved in the protection and preservation of neuronal functions, probably through the production of neurotrophic factors in the brain. On the other hand, neuroactive 5α-reduced steroids promote glial cell differentiation, resulting in enhancement of their ability to produce brain-derived neurotrophic factor (BDNF). Based on these findings, polyamines are assumed to stimulate the expression of the gene encoding steroid 5α-reductase (5α-R), which can induce the production of neuroactive 5α-reduced steroids in glial cells. The effects of polyamines on 5α-R mRNA levels in C6 glioma cells were examined as a model experiment. In consequence, spermine (SPM) and spermidine (SPD), but not putrescine (PUT), have been shown to elevate 5α-R mRNA levels without activating the 5α-R promoter. Furthermore, SPM increased 5α-R mRNA levels under the conditions in which the mRNA biosynthesis was inhibited. Therefore, it can be speculated that polyamines increase 5α-R mRNA levels as a consequence of suppressing the degradation of mRNA. © 2014 International Federation for Cell Biology.

Sagara T.,Shokei College | Nishibori N.,Shikoku Junior College | Kishibuchi R.,Shikoku University | Itoh M.,Shikoku University | And 2 more authors.
Journal of Applied Phycology | Year: 2015

The abnormal accumulation of iron in the brain has been suggested to be toxic to neuronal cells and proposed as a possible cause of neurodegenerative disorders. Particularly, studies on the pathogenesis of neurodegenerative diseases have suggested that the excessive accumulation of iron in the specific brain regions may be responsible for neurodegenerative changes associated with the pathogenesis of Alzheimer's, Parkinson's, and Huntington's diseases. As a part of studies searching for natural substances protecting neuronal cells against the iron-evoked toxic injury, an aqueous extract containing the non-protein components of the cyanobacterium Arthrospira (Spirulina) platensis, designated “the protein-deprived extract”, was prepared, and its effect on the iron-evoked damage to PC12 cells was examined in an in vitro model experiment. The protein-deprived extract caused a protective effect against the iron-evoked damage to PC12 cells as a consequence of preventing the free radical-evoked DNA degradation. Further studies showed that the extract has antioxidant and free radical-scavenging activities, which might be based on polyphenolic compounds in the extract. Thus, polyphenolic compounds contained in A. platensis are suggested to be potentially active substances responsible for the protective effect of Arthrospira extract against the iron-evoked neurotoxicity and possibly for the protection of neurodegenerative disorders induced by excessive iron accumulation in the brain. © 2014, Springer Science+Business Media Dordrecht.

Morita K.,Shikoku University | Itoh M.,Shikoku University | Itoh M.,Tokushima University | Nishibori N.,Shikoku Junior College | And 2 more authors.
Applied Biochemistry and Biotechnology | Year: 2014

Blue-green algae are known to contain biologically active proteins and non-protein substances and considered as useful materials for manufacturing the nutritional supplements. Particularly, Spirulina has been reported to contain a variety of antioxidants, such as flavonoids, carotenoids, and vitamin C, thereby exerting their protective effects against the oxidative damage to the cells. In addition to their antioxidant actions, polyphenolic compounds have been speculated to cause the protection of neuronal cells and the recovery of neurologic function in the brain through the production of brain-derived neurotrophic factor (BDNF) in glial cells. Then, the protein-deprived extract was prepared by removing the most part of protein components from aqueous extract of Spirulina platensis, and the effect of this extract on BDNF gene transcription was examined in C6 glioma cells. Consequently, the protein-deprived extract was shown to cause the elevation of BDNF mRNA levels following the expression of heme oxygenase-1 (HO-1) in the glioma cells. Therefore, the non-protein components of S. platensis are considered to stimulate BDNF gene transcription through the HO-1 induction in glial cells, thus proposing a potential ability of the algae to indirectly modulate the brain function through the glial cell activity. © 2014, Springer Science+Business Media New York.

Itoh M.,Shikoku University | Nishibori N.,Shikoku Junior College | Sagara T.,Shikoku Junior College | Horie Y.,Kohken Co. Inc. | And 2 more authors.
Phytotherapy Research | Year: 2012

Brown rice fermented with Aspergillus oryzae, designated as FBRA, is a dietary fiber-rich food, and fully appreciated as one of the prebiotics, which are generally considered to be beneficial to the health of the body, because of stimulating the growth and/or the activity of bacteria in the digestive system. To assess the effectiveness of FBRA as a functional food, the direct effect of FBRA extract on human colorectal tumor cells was examined. The exposure of HCT116 cells to FBRA extract reduced their viabilities in a concentration- dependent manner, and the reduction of the cell viability might be attributed to the induction of apoptosis probably through the oxidative damage to the cells. Further studies showed that FBRA extract caused a significant elevation of Bax protein and a slight reduction of Bcl2 protein levels, and furthermore caused the activation of caspase-3 in the cells. Thus, it seems reasonable to conclude that FBRA extract can exert oxidative damage to the cells, resulting in apoptotic cell death by activating the mitochondrial pathway in human colorectal tumor cells. Therefore, daily intake of FBRA can be expected to be beneficial for preventing carcinogenesis and/or suppressing tumor growth in the digestive tract. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.

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