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Ito M Matsuka N Izuka M Haito S Sakai Y Nakamura R Segawa H Kuwahata M Yamamoto H Pike WJ Miyamoto K 《American journal of physiology. Cell physiology》2005,288(4):C921-C931
Osteoclasts possess inorganic phosphate (Pi) transport systems to take up external Pi during bone resorption. In the present study, we characterized Pi transport in mouse osteoclast-like cells that were obtained by differentiation of macrophage RAW264.7 cells with receptor activator of NF-B ligand (RANKL). In undifferentiated RAW264.7 cells, Pi transport into the cells was Na+ dependent, but after treatment with RANKL, Na+-independent Pi transport was significantly increased. In addition, compared with neutral pH, the activity of the Na+-independent Pi transport system in the osteoclast-like cells was markedly enhanced at pH 5.5. The Na+-independent system consisted of two components with Km of 0.35 mM and 7.5 mM. The inhibitors of Pi transport, phosphonoformic acid, and arsenate substantially decreased Pi transport. The proton ionophores nigericin and carbonyl cyanide p-trifluoromethoxyphenylhydrazone as well as a K+ ionophore, valinomycin, significantly suppressed Pi transport activity. Analysis of BCECF fluorescence indicated that Pi transport in osteoclast-like cells is coupled to a proton transport system. In addition, elevation of extracellular K+ ion stimulated Pi transport, suggesting that membrane voltage is involved in the regulation of Pi transport activity. Finally, bone particles significantly increased Na+-independent Pi transport activity in osteoclast-like cells. Thus, osteoclast-like cells have a Pi transport system with characteristics that are different from those of other Na+-dependent Pi transporters. We conclude that stimulation of Pi transport at acidic pH is necessary for bone resorption or for production of the large amounts of energy necessary for acidification of the extracellular environment. Na+-dependent phosphate cotransporter; RAW264.7; phosphate uptake 相似文献
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Dutta Sulagna Sengupta Pallav Izuka Emmanuel Menuba Ifeanyi Jegasothy Ravindran Nwagha Uchenna 《Molecular and cellular biochemistry》2020,463(1-2):57-66
Molecular and Cellular Biochemistry - Membrane lipids regulate the structure and function of G protein-coupled receptors (GPCRs). Previously we have shown that membrane cholesterol regulates the... 相似文献
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Shohei Kuwata Kei Ohkubo Shun Kumamoto Naoto Yamaguchi Naoki Izuka Kaeko Murota Toshifumi Tsujiuchi Masao Iwamori Nobuyuki Fukushima 《Biochemical and biophysical research communications》2013
Lysophosphatidic acid (LPA) is an extracellular lipid mediator consisting of a fatty acid and a phosphate group linked to the glycerol backbone. Here, we show that 1-oleoyl- and 1-palmitoyl-LPA, but not 1-stearoyl- or alkyl-LPA, enhance HNOA ovarian cancer cell survival. Other lysophospholipids with oleic or lauric acid, but not stearic acid, also induce the survival effects. HNOA cells have the lipase activities that cleave LPA to generate fatty acid. Oleic acid stimulates HNOA cell survival via increased glucose utilization. Our findings suggest that extracellular lysolipid metabolism might play an important role in HNOA cell growth. 相似文献
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Use of bacterial gamma-glutamyltranspeptidase for enzymatic synthesis of gamma-D-glutamyl compounds 总被引:1,自引:0,他引:1
Suzuki H Izuka S Minami H Miyakawa N Ishihara S Kumagai H 《Applied and environmental microbiology》2003,69(11):6399-6404
An enzymatic method for synthesizing various gamma-D-glutamyl compounds efficiently and stereospecifically involving bacterial gamma-glutamyltranspeptidase (EC 2.3.2.2) with D-glutamine as a gamma-glutamyl donor was developed. With D-glutamine as a gamma-glutamyl donor instead of L-glutamine in gamma-glutamyltaurine synthesis, by-products such as gamma-glutamylglutamine and gamma-glutamyl-gamma-glutamyltaurine were not synthesized and the yield of gamma-glutamyltaurine dramatically increased from 25 to 71%. It was also shown that the purification could be simplified without these gamma-glutamyl by-products. The possibility of synthesizing various gamma-D-glutamyl compounds was also shown. 相似文献
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The yliA, -B, -C, and -D genes of Escherichia coli K-12 encode a novel glutathione importer with an ATP-binding cassette 下载免费PDF全文
Glutathione protects cells and organisms from oxygen species and peroxides and is indispensable for aerobically living organisms. Moreover, it acts against xenobiotics and drugs by the formation and excretion of glutathione S conjugates. In this study, we show that the yliA, -B, -C, and -D genes of Escherichia coli K-12 encode a glutathione transporter with the ATP-binding cassette. The transporter imports extracellular glutathione into the cytoplasm in an ATP-dependent manner. This transporter, along with gamma-glutamyltranspeptidase, has an important role in E. coli growth with glutathione as a sole sulfur source. 相似文献
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M Izuka M Fukushima A Taniguchi Y Nakai H Suzuki T Kawakita S Kawamata O Kajimoto K Tsuda N Nagaki M Murakami Y Seino 《Hormones et métabolisme》2007,39(1):41-45
Impaired fasting glucose (IFG) represents risk of development of diabetes (DM) and its complications. We investigated insulin secretion and insulin sensitivity in 403 IFG subjects divided into three levels of 2-hour postchallenge glucose (2-h PG) to clarify the factors responsible in the development of glucose intolerance in Japanese IFG. Nearly 60% of the subjects at annual medical check-up with FPG of 6.1-7.0 mmol/l at the first screening were diagnosed by 75 g oral glucose tolerance test (OGTT) to have impaired glucose tolerance (IGT; FPG <7.0 mmol/l and 7.8 mmol/l <2-h PG <11.1 mmol/l) or DM (isolated postchallenge hyperglycemia (IPH); FPG <7.0 mmol/l and 11.1 mmol/l <2-h PG level). The primary factor in the decreased glucose tolerance was a decrease in early-phase insulin, with some contribution of increasing insulin resistance. In addition, IFG/IGT and IFG/IPH subjects showed a compensatory increase in basal insulin secretion sufficient to keep FPG levels within the non-diabetic range. IFG is composed of three different categories in basal, early-phase insulin secretion, and insulin sensitivity. 相似文献
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