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981.
Enhancement of differentiation induction of mouse myelomonocytic leukemic cells by extracellular ATP
Masahiro Yamaguchi Kazunori Hirayoshi Minoru Okuma Kazuhiro Nagata 《Journal of cellular physiology》1994,159(3):441-449
We examined the effect of ATP on the terminal differentiation of mouse myelomonocytic leukemic M1 cells to macrophages. Although ATP alone did not induce M1 cell differentiation, addition of ATP with the differentiation inducer, interleukin 6 (IL-6), enhanced the induction of differentiation by IL-6 about twofold. Comparison among several adenine nucleotides revealed that the order of effectiveness on differentiation enhancement was ATP > ADP > AMP ≥ adenosine. Using reactive blue 2, a P2 receptor antagonist, we confirmed that the effect of ATP on the stimulation of differentiation was mediated through the P2 purinergic receptor. Examination of cytosolic [Ca2+] elevation by ATP and comparison of potency of differentiation enhancement among several ATP analogs demonstrated that the effect of differentiation enhancement was mediated through P2y purinergic receptors expressed on M1 cell surface. Within 3 h of exposure, ATP alone slightly increased the expression of differentiation-related immediate early response genes, c-myc and JunB, and ATP also enhanced the IL-6–induced expression of these genes. Induction of JunB expression by ATP analogs correlated with their potency of differentiation enhancement, which suggested that induction of JunB by ATP is one of signaling pathways involved in the exertion of its differentiation-enhancing effect. © 1994 wiley-Liss, Inc. 相似文献
982.
Primary cultured rat hepatocytes in a membrane-supported collagen sandwich maintained their normal cell morphology and high level of albumin secretion for over 56 days. It was found that the existence of an upper layer of collagen gel is crucial for long-term culture and that the transference of cellular nutrients between the culture media and hepatocytes from both the upper and the lower sides of gel layers promotes albumin secretion. These facts suggest that the membrane-supported collagen sandwich mimics well thein vivo environment of hepatocytes. This method has great potential for the long-term culture of primary cells. 相似文献
983.
Rapid Changes in Polyphosphoinositide Metabolism in Pea in Response to Fungal Signals 总被引:5,自引:0,他引:5
Toyoda Kazuhiro; Shiraishi Tomonori; Yamada Tetsuji; Ichinose Yuki; Oku Hachiro 《Plant & cell physiology》1993,34(5):729-735
Effects of the elicitor and/or suppressor from Mycosphaerellapinodes on polyphosphoinositide metabolism (PI metabolism) inpea were examined both in vivo and in vitro. The elicitor induceda rapid and biphasic increase in levels of phosphatidylinositol-4,5-bisphosphate(PtdInsP2) and inositol 1,4,5-trisphosphate (IP3) in epicotyltissues that was apparent within 15 min. A transient increasein levels of PtdInsP2 and IP3 was detected immediately in elicitor-treatedplasma membranes. However, the concomitant presence of suppressorwith elicitor resulted in inhibition of these increases bothin vivo and in vitro. These findings suggest that the elicitorrapidly activates phosphatidylinositol kinase, phosphatidylinositol-4-monophosphatekinase and phospholipase C, which are involved in PI metabolism,whereas the suppressor markedly inhibits these enzymes. Neomycin,a known inhibitor of phospholipase C, blocked the elicitor-inducedaccumulation both of IP3 and pisatin and it also induced localsusceptibility in pea tissues that resembled that of the fungalsuppressor. From these results, it appears that rapid changesin PI metabolism are indispensable in the signal transductionrelated to defense responses of pea plants. (Received January 18, 1993; Accepted May 13, 1993) 相似文献
984.
Hiroshi Yamasaki Myung-Sup Lee Takaaki Tanaka Kazuhiro Nakanishi 《Applied microbiology and biotechnology》1993,39(1):21-25
To improve the performance of cross-flow membrane filtration of pullulan broth from Aureobasidium pullulans, the effect of the cultivation conditions was examined. In particular, the sucrose concentration in the medium was changed over a wide range. By decreasing the sucrose concentration the distribution of morphology of the microbial cells in the broth changed; the yeast-like form became predominant and, as a result, the specific resistance of the microbial cake was lowered. When the broth was fermented with a sucrose concentration of 2.5% or lower, the filtration characteristics were greatly improved by periodic closure of permeation during cross-flow filtration.On leave from Hayashibara Co., Ltd., Amase-minamimachi, Okayama 700, Japan
Correspondence to: K. Nakanishi 相似文献
985.
Thp is a large deletion on chromosome 17 which includes the maternal lethal gene Tme. Documentation of inheritance patterns suggests that Tme is an imprinted gene which is required for viability; maternal deletion is lethal while paternal deletion is viable. However, paternal transmission of Thp is rarely the expected 50%. We show here that paternally inherited Thp is lethal in some strains, providing evidence of an incompletely penetrant, dosage sensitive lethal allele of a locus that probably maps to the hairpin tail region of chr. 17. Interpretation of the various phenotypes associated with loss of the putative Tme gene, lgf2r, may need to be revised in view of these observations. Dev Genet 20:23–28, 1997. © 1997 Wiley-Liss, Inc. 相似文献
986.
Rie Hosoi Toshio Matsuda Shoichi Asano Hiroaki Nakamura Hitoshi Hashimoto Kazuhiro Takuma Akemichi Baba 《Journal of neurochemistry》1997,69(5):2189-2196
Abstract: There are two α-subunit isoforms (α1 and α2) and two β-subunit isoforms (β1 and β2) of Na+ ,K+ -ATPase in astrocytes, but the functional heterodimer composition is not known. Ouabain (0.5–1.0 m M ) increased the levels of α1 and β1 mRNAs, whereas it decreased those of α2 and β2 mRNAs in cultured rat astrocytes. The increases in α1 and β1 mRNAs were observed at 6–48 h after addition of the inhibitor. Immunochemical analyses showed that ouabain increased α1 and β1, but not α2 and β2, proteins, and that the isoforms in control and ouabain-treated cultures were of glial origin. Low extracellular K+ and monensin (20 µ M ) mimicked the effect of ouabain on α1 mRNA. The ouabain-induced increase in α1 mRNA was blocked by the protein synthesis inhibitor cycloheximide (10 µ M ), the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane- N,N,N',N' -tetraacetic acid tetraacetoxymethyl ester (30 µ M ), and the calcineurin inhibitor FK506 (1 n M ). These findings indicate that chronic inhibition of Na+ ,K+ -ATPase up-regulates the α1 and β1, but not α2 and β2, isoforms in astrocytes, suggesting a functional coupling of α1β1 complex. They also suggest that intracellular Na+ , Ca2+ , and calcineurin may be involved in ouabain-induced up-regulation of the enzyme in astrocytes. 相似文献
987.
Xiao-Jian Xia Li-Feng Huang Yan-Hong Zhou Wei-Hua Mao Kai Shi Jian-Xiang Wu Tadao Asami Zhixiang Chen Jing-Quan Yu 《Planta》2009,230(6):1185-1196
Brassinosteroids (BRs) are a new group of plant growth substances that promote plant growth and productivity. We showed in
this study that improved growth of cucumber (Cucumis sativus) plants after treatment with 24-epibrassinolide (EBR), an active BR, was associated with increased CO2 assimilation and quantum yield of PSII (ΦPSII). Treatment of brassinazole (Brz), a specific inhibitor for BR biosynthesis, reduced plant growth and at the same time decreased
CO2 assimilation and ΦPSII. Thus, the growth-promoting activity of BRs can be, at least partly, attributed to enhanced plant photosynthesis. To understand
how BRs enhance photosynthesis, we have analyzed the effects of EBR and Brz on a number of photosynthetic parameters and their
affecting factors, including the contents and activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Northern
and Western blotting demonstrated that EBR upregulated, while Brz downregulated, the expressions of rbcL, rbcS and other photosynthetic genes. In addition, EBR had a positive effect on the activation of Rubisco based on increased maximum
Rubisco carboxylation rates (V
c,max), total Rubisco activity and, to a greater extent, initial Rubisco activity. The accumulation patterns of Rubisco activase
(RCA) based on immunogold-labeling experiments suggested a role of RCA in BR-regulated activation state of Rubisco. Enhanced
expression of genes encoding other Calvin cycle genes after EBR treatment may also play a positive role in RuBP regeneration
(J
max), thereby increasing maximum carboxylation rate of Rubisco (V
c,max). Thus, BRs promote photosynthesis and growth by positively regulating synthesis and activation of a variety of photosynthetic
enzymes including Rubisco in cucumber. 相似文献
988.
Etienne Jean Faye Kazuhiro Kogame Satoshi Shimada Shigeo Kawaguchi Michio Masuda 《Phycological Research》2008,56(2):115-126
A new red alga Meristotheca imbricata Faye et Masuda (Solieriaceae, Gigartinales) was described on the basis of specimens collected from southern Japan. Although this species might have been for a long time included in the concept of M. coacta Okamura, until recently a very poorly known alga, it is distinguished from the latter by the following features: (i) each thallus consists of one primary blade and several secondary blades, the latter arising from the apical or subapical portion of terminal segments of the primary blade; (ii) the individual blades are repeatedly dichotomously divided into linear segments of which margins are neither undulate nor crispate, and are fleshy, imbricate, frequently anastomosing and often acervate; (iii) each tetrasporangial initial is attached by a basal pit-connection to the parental cell, and the position of the pit-connection changes from basal to lateral by inward growth of the tetrasporangium; and (iv) the carpogonial branches sometimes have a one-celled sterile lateral. 相似文献
989.
Keisuke Shigeta Masanori Hasegawa Takako Hishiki Yoshiko Naito Yuto Baba Shuji Mikami Kazuhiro Matsumoto Ryuichi Mizuno Akira Miyajima Eiji Kikuchi Hideyuki Saya Takeo Kosaka Mototsugu Oya 《The EMBO journal》2023,42(4)
Drug resistance contributes to poor therapeutic response in urothelial carcinoma (UC). Metabolomic analysis suggested metabolic reprogramming in gemcitabine‐resistant urothelial carcinoma cells, whereby increased aerobic glycolysis and metabolic stimulation of the pentose phosphate pathway (PPP) promoted pyrimidine biosynthesis to increase the production of the gemcitabine competitor deoxycytidine triphosphate (dCTP) that diminishes its therapeutic effect. Furthermore, we observed that gain‐of‐function of isocitrate dehydrogenase 2 (IDH2) induced reductive glutamine metabolism to stabilize Hif‐1α expression and consequently stimulate aerobic glycolysis and PPP bypass in gemcitabine‐resistant UC cells. Interestingly, IDH2‐mediated metabolic reprogramming also caused cross resistance to CDDP, by elevating the antioxidant defense via increased NADPH and glutathione production. Downregulation or pharmacological suppression of IDH2 restored chemosensitivity. Since the expression of key metabolic enzymes, such as TIGAR, TKT, and CTPS1, were affected by IDH2‐mediated metabolic reprogramming and related to poor prognosis in patients, IDH2 might become a new therapeutic target for restoring chemosensitivity in chemo‐resistant urothelial carcinoma. 相似文献
990.
After protein phosphorylation on certain serine or threonine residues preceding a proline (pSer/Thr-Pro), the function of certain phosphorylated protein is further regulated by cis-trans conformational change. Due to the lack of any tool to detect such two conformations in cells, however, it is not even known whether any cis or trans conformation exists in vivo, not to mention their conformation-specific functions or regulation. We developed a novel peptide chemistry technology to generate the first pair of antibodies that can distinguish cis from trans pThr231-Pro tau. Cis, but not trans, pThr231-tau appears early in mild cognitive impairment (MCI) neurons and further accumulates in only degenerating neurons as Alzheimer disease (AD) progresses, localizing to dystrophic neurites, which are known to correlate well with memory loss. Unlike trans p-tau, the cis cannot promote microtubule assembly, and is more resistant to dephosphorylation and degradation and more prone to aggregation. Pin1 accelerates cis to trans isomerization to prevent tau pathology in AD. Thus, during MCI and AD development, cis pThr231-Pro tau is the earliest detectable pathogenic tau conformation and antibodies and vaccines against the pathogenic cis p-tau may be used for the early diagnosis and treatment of AD. These findings offer in vivo approach to study conformational regulation of Pro-directed phosphorylation signaling. 相似文献