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51.
52.
Abstract: Previous work has shown that nerve growth factor (NGF) stimulates the phosphorylation of the ribosomal protein S6 in PC12 cells. In this study, we show that S6 kinase activity is also present in purified PC12 cell nuclei. This activity was increased by treatment of the cells with NGF and, to a lesser extent, by treatment with epidermal growth factor. The NGF-stimulated activity was obtained from nuclear extracts and some of its characteristics described. The increase in activity was prevented by treatment of the cells with rapamycin or with wortmannin, and the overall activity could be precipitated by antibodies directed against the p85S6K . These data indicate that p85S6K is the NGF-stimulated S6 kinase in PC12 cell nuclei. The presence of S6 protein in the nucleus of PC12 cells has been confirmed and evidence is presented that suggests that it is identical to a protein called SMP reported some years ago. 相似文献
53.
54.
Ras-Regulated Hypophosphorylation of the Retinoblastoma Protein Mediates Neuronal Differentiation in PC12 Cells 总被引:2,自引:0,他引:2
†HongZhen Li ‡Hiroshi Kawasaki ‡Eisuke Nishida Seisuke Hattori Shun Nakamura 《Journal of neurochemistry》1996,66(6):2287-2294
Abstract: To investigate the role of the retinoblastoma protein pRB in neuronal differentiation, we have measured the accumulation of hypophosphorylated pRB in PC12 cells stimulated by nerve growth factor (NGF). NGF induced the accumulation of hypophosphorylated pRB within 30 min and the level peaked after 12 h. Viral Kiras, cyclic AMP (cAMP), and 12- O -tetradecanoylphorbol 13-acetate (TPA) also induced the hypophosphorylation of pRB, but epidermal growth factor and interleukin-6 did not. The extent of hypophosphorylation of pRB correlated well with the capacity of these factors to stimulate neurite outgrowth. The constitutively activated Ras induced persistent shift of the phosphorylation state of pRB toward hypophosphorylation. A dominant negative form of cHa-Ras suppressed significantly induction of the hypophosphorylation of pRB by NGF, but not by cAMP. Taken together, these results suggest that the hypophosphorylation of pRB triggered by NGF is mediated by a Ras-dependent pathway. Furthermore, microinjection of a monoclonal antibody specific for the hypophosphorylated form of pRB blocked the neurite outgrowth initiated by NGF. These results suggest a crucial role of pRB in withdrawal of cells from the cell cycle and in neuronal differentiation of PC12 cells. 相似文献
55.
Effects of interleukin-12 on in vitro culture with interleukin-2 of regional lymph node lymphocytes from lung cancer patients 总被引:2,自引:0,他引:2
T. Hanagiri Mitsuhiro Takenoyama Takashi Yoshimatsu Chikashi Hirashima Ichiro Yoshino Kozo Nakanishi Akira Nagashima Kikuo Nomoto Kosei Yasumoto 《Cancer immunology, immunotherapy : CII》1996,43(2):87-93
In the present study, we carried out a functional analysis of regional lymph node lymphocytes (RLNL) from patients with lung
cancer after in vitro activation by interleukin-2 (IL-2) and interleukin-12 (IL-12). IL-12 (100 U/ml) enhanced both the proliferation
and cytotoxic activity of RLNL in a culture with low doses of IL-2 (5 – 10 JRU/ml). After comparing an RLNL culture with a
low dose of IL-2 alone, a higher proportion of CD8+ cells and CD56+ cells and a lower proportion of CD4+ cells were found in the culture with both IL-12 and a low dose of IL-2. Such a combination of the cytokines effectively activated
RLNL in terms of the expression of IL-2 receptors. In the culture condition of IL-12 and a low dose of IL-2, a synergistic
effect was observed in the production of such cytokines as interferon γ, tumor necrosis factor α (TNFα), and TNFβ, as well
as in tumor cytotoxicity. However, the addition of IL-12 inhibited the cytotoxicity of RLNL in the culture with a high dose
of IL-2 (100 JRU/ml). This inhibition is considered to be partially due to the endogenous production of TNFα by lymphocytes,
because the neutralization of TNFα bioactivity partially restored the cytotoxic activities of RLNL. Furthermore, in the presence
of hydrocortisone, IL-12 synergistically enhanced the cytotoxic activity of RLNL cultured with a high dose of IL-2. These
results provide useful information about the improvement of adoptive immunotherapy against cancer using RLNL.
Received: 2 February 1996 / Accepted: 30 July 1996 相似文献
56.
Masashi Yamada Toshihiko Ikeuchi Saburo Aimoto Dr. Hiroshi Hatanaka 《Neurochemical research》1996,21(7):815-822
PC12h-R cell, a subclone of PC12 cells, exhibited a neuron-like phenotype, including neurite outgrowth and increased acetylcholinesterase
activity, in response to epidermal growth factor (EGF) as well as nerve growth factor (NGF). We examined the mechanism by
which EGF induced the neuronal differentiation in PC12h-R cells. The EGF-induced neuronal differentiation of PC12h-R cells
was not blocked by K252a, whereas that induced by NGF was. EGF induced sustained tyrosine phosphorylation of the EGF receptor
in PC12h-R cells, but not in the parent PC12h cells, which do not show neuronal differentiation in response to EGF. In addition,
the rate of EGF-induced down-regulation of the EGF receptor in PC12h-R cells was decreased compared with that in PC12h cells.
Furthermore, we found that the duration of EGF-induced tyrosine phosphorylation of the EGF receptor in PC12h-R cells was similar
to that of NGF-induced tyrosine phosphorylation of p140
trkA in PC12h cells. The EGF-induced phosphorylation of the EGF receptor in PC12h cells was less sustained than that of p140
trkA by NGF in PC12h cells. These findings suggested that the EGF-induced neuronal differentiation of PC12h-R cells is due to
the sustained activation of the EGF receptor, resulting from the decreased down-regulation of the EGF receptor and that the
duration of the receptor tyrosine kinase activity determines the cellular responses of PC12 cells. We concluded that sustained
activation of the receptor tyrosine kinase induces neuronal differentiation, although transient activation promotes proliferation
of PC12 cells.
Special issue dedicated to Dr. Hans Thoenen. 相似文献
57.
Kazuhito Hisatsune Seiichi Kondo Takehiro Iguchi Teruyo Ito Keiichi Hiramatsu 《Microbiology and immunology》1996,40(9):621-626
Structural and serological studies were performed with the lipopolysaccharide (LPS) expressed by Escherichia coli K12 strains No. 30 and No. 64, into which cosmid clones derived from Vibrio cholerae O1 NIH 41 (Ogawa) and NIH 35A3 (Inaba) had been introduced, respectively. The two recombinant strains, No. 30 (Ogawa) and No. 64 (Inaba), produced LPS that included, in common, the O-polysaccharide chain composed of an α(1 → 2)-linked N-(3-deoxy-L -glycero-tetronyl)-D -perosamine (4-amino-4,6-dideoxy-D -manno-pyranose) homopolymer attached to the core oligosaccharide of the LPS of E. coli K12. Structural analysis revealed the presence of N-(3-deoxy-L -glycero-tetronyl)-2-O-methyl-D -perosamine at the non-reducing terminus of the O-polysaccharide chain of LPS from No. 30 (Ogawa) but not from No. 64 (Inaba). Serological analysis revealed that No. 30 (Ogawa) and No. 64 (Inaba) LPS were found to share the group antigen factor A of V. cholerae O1. They were distinguished by presence of the Ogawa antigen factor B [co-existing with relatively small amounts of the Inaba antigen factor (c)] in the former LPS and the Inaba antigen factor C in the latter LPS. It appears, therefore, that No. 30 (Ogawa) and No. 64 (Inaba) have O-antigenic structures that are fully consistent with the AB(c) structure for the Ogawa and the AC structure for the Inaba O-forms of V. cholerae O1, respectively. Thus, the present study clearly confirmed our previous finding that the Ogawa antigenic factor B is substantially related to the 2-O-methyl group at the non-reducing terminus of the α(1 → 2)-linked N-(3-deoxy-L -glycero-tetronyl)-D -perosamine homopolymer that forms the O-polysaccharide chain of LPS of V. cholerae O1 (Ogawa). 相似文献
58.
Because vitamin B12 and Ni are known to interact and because of the similar metabolic roles of vitamin B12 and folate, an experiment was performed to determine the effect of dietary folate on Ni deprivation in rats. A 2×2 factorially
arranged experiment used groups of nine weanling Sprague-Dawley rats. Dietary variables were Ni, as NiCl2·6H2O, 0 or 1 μg/g; and folic acid, 0 or 2 mg/kg. The basal diet, based on skim milk, contained less than 20 ng Ni/g. After 54
d, an interaction between dietary Ni and folate affected several variables including erythrocyte folate, plasma amino acids,
and femur trace elements. For example, folate deprivation decreased erythrocyte folate; folate supplementation to the Ni-supplemented
rats caused a larger increase in erythrocyte folate concentration than did folate supplementation to the Ni-deprived rats.
Also, dietary Ni affected several plasma amino acids important in one-carbon metabolism (e.g., Ni deprivation increased the
plasma concentrations of glycine and serine). This study shows that dietary Ni, folate, and their interaction can affect variables
associated with one-carbon metabolism. This study does not show a specific site of action of Ni but it indicates that Ni may
be important in processes related to the vitamin B12-dependent pathway in methionine metabolism, possibly one-carbon metabolism.
US Department of Agriculture, Agricultural Research Service, Northern Plans Area is an equal opportunity/affirmative action
employer and all agency services are available without discrimination. 相似文献
59.
A novel type of DNA-binding protein interacts with a conserved sequence in an early nodulin ENOD12 promoter 总被引:3,自引:0,他引:3
60.
利用标记基因选配褐壳蛋鸡配套杂交亲本 总被引:5,自引:0,他引:5
程光潮 刘树俊 段章雄 张琦 王力 刘坤凡CHENG Guang-Chao LIU Shu-Jun DUAN Zhang-Xiong ZHANG Qi WANG Li LIU Kun-Fan 《遗传》1996,18(2):28-32
应用本实验室研制的抗鸡红细胞抗原单价血清(4个位点, 14个等位基因)和DNA指纹技术,对我们组配成功的一个褐壳蛋鸡配套系统的5个亲本进行了群体遗传学分析。结果表明,由标记基因测定所提供的亲本品系遗传差异的大小, 与这些品系实际杂交效果的优劣相一致,证实了标记辅助选种方法有的效性。 相似文献