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991.
Roles of the Ras-MEK-mitogen-activated protein kinase and phosphatidylinositol 3-kinase-Akt-mTOR pathways in Jaagsiekte sheep retrovirus-induced transformation of rodent fibroblast and epithelial cell lines 总被引:2,自引:0,他引:2 下载免费PDF全文
Jaagsiekte sheep retrovirus (JSRV) is the causative agent of ovine pulmonary adenocarcinoma (OPA), a transmissible lung cancer of sheep. The virus can induce tumors rapidly, and we previously found that the JSRV envelope protein (Env) functions as an oncogene, because it can transform mammalian and avian fibroblast cell lines. (N. Maeda, Proc. Natl. Acad. Sci. USA 98:4449-4454, 2001). The molecular mechanisms of JSRV Env transformation are of considerable interest. Several reports suggested that the phosphatidylinositol 3-kinase/Akt pathway is important for transformation of mammalian fibroblasts but not for chicken fibroblasts. In this study, we found that Akt/mTOR is involved in JSRV transformation of mouse NIH 3T3 fibroblasts, because treatment with the mTOR inhibitor rapamycin reduced transformation. We also found that H/N-Ras inhibitor FTI-277 and MEK1/2 inhibitors PD98059 and U0126 strongly inhibited JSRV transformation of NIH 3T3 fibroblasts, suggesting that the H/N-Ras-MEK-mitogen-activated protein kinase (MAPK) p44/42 pathway is necessary for the transformation. In RK3E epithelial cells, the MEK1/2 inhibitors also eliminated transformation, but FTI-277 only partially inhibited transformation. It was noteworthy that p38 MAPK inhibitors enhanced JSRV transformation in both fibroblasts and epithelial cells. Treatment of transformed cells with p38 inhibitors both increased levels of phospho-MEK1/2 and phospho-p44/42 and induced rapid enhancement of the transformed phenotype. Immunohistochemical staining of tumor tissues from naturally and experimentally induced OPA and naturally occurring enzootic nasal adenocarcinoma revealed strong activation of MAPK p44/42 in all cases examined. However, p38 activation was not generally observed. These results indicate that signaling through two pathways (in particular, H/N-Ras-MEK-MAPK and, to a lesser extent, Akt-mTOR) is important for JSRV-induced transformation and that p38 MAPK has a negative regulatory effect on transformation, perhaps via MEK1/2 and p44/42. 相似文献
992.
Intersubgenomic heterosis in seed yield potential observed in a new type of Brassica napus introgressed with partial Brassica
rapa genome 总被引:2,自引:0,他引:2
Qian W Chen X Fu D Zou J Meng J 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,110(7):1187-1194
This paper reports the observation on the intersubgenomic heterosis for seed yield among hybrids between natural Brassica napus (AnAnCnCn) and a new type of B. napus with introgressions of genomic components of Brassica rapa (ArAr). This B. napus was selected from the progeny of B. napus × B. rapa and (B. napus × B. rapa) × B. rapa based on extensive phenotypic and cytological observation. Among the 129 studied partial intersubgenomic hybrids, which were obtained by randomly crossing 13 lines of the new type of B. napus in F3 or BC1F3 to 27 cultivars of B. napus from different regions as tester lines, about 90% of combinations exceeded the yield of their respective tester lines, whereas about 75% and 25% of combinations surpassed two elite Chinese cultivars, respectively. This strong heterosis was further confirmed by reevaluating 2 out of the 129 combinations in a successive year and by surveying hybrids between 20 lines of the new type of B. napus in BC1F5 and its parental B. napus in two locations. Some DNA segments from B. rapa were identified with significant effects on seed yield and yield components of the new type of B. napus in BC1F5 and intersubgenomic hybrids in positive or negative direction. It seems that the genomic components introgressed from B. rapa contributed to improvement of seed yield of rapeseed. 相似文献
993.
铁代谢与铁调素hepcidin 总被引:10,自引:0,他引:10
铁是机体必需的营养元素。然而,铁过载则导致细胞的损伤。由于生物体缺少排泄铁的机制,因而,肠铁吸收的调控便成为维持机体铁稳态的关键。新近研究发现hepcidin对机体铁稳态的调节起着至关重要的作用,被人们称为铁调节激素。Hepcidin主要在肝细胞中合成,之后分泌至血液将体内铁需要的信号传至小肠,调控肠铁的吸收。这一过程主要通过调节小肠铁转运相关蛋白的表达而实现。任何影响hepcidin表达的因素都可能破坏体内的铁平衡,造成铁代谢相关疾病。 相似文献
994.
Raf kinase inhibitor protein (RKIP) was originally identified as a protein that bound membrane phospholipids and was named phosphatidylethanolamine binding protein-2 (PEBP-2). RKIP was than identified as a protein that bound Raf and blocked its ability to phosphorylate MEK, thus earning its new name of RKIP. Subsequent to identification of its role in the Raf:MEK pathway, RKIP has been demonstrated to regulate several other signaling pathways including G-protein signaling and NF-kappaB signaling. Its involvement in several signaling pathways has engendered RKIP to contribute to several physiological processes including membrane biosynthesis, spermatogenesis, neural development, and apoptosis. RKIP is expressed in many tissues including brain, lung, and liver and thus, dysregulation of RKIP expression or function has potential to contribute to pathophysiology in these tissues. Loss of RKIP expression in prostate cancer cells confers a metastatic phenotype on them. Additionally, restoration of RKIP expression in a metastatic prostate cancer cell line does not effect primary tumor growth, but it does inhibit prostate cancer metastasis. These parameters identify RKIP as a metastasis suppressor gene. In this review, the biology and pathophysiology of RKIP is described. 相似文献
995.
Interstitium contains a matrix of fibrous molecules that creates considerable resistance to water and solutes in series with the microvessel wall. On the basis of our preliminary studies, by using laser-scanning confocal microscopy and a theoretical model for interstitial transport, we determined both microvessel solute permeability (P) and solute tissue diffusion coefficient (D) of alpha-lactalbumin (Stokes radius 2.01 nm) from the rate of tissue solute accumulation and the radial concentration gradient around individually perfused microvessel in frog mesentery. P(alpha-lactalbumin) is 1.7 +/- 0.7(SD) x 10(-6) cm/s (n = 6). D(t)/D(free) for alpha-lactalbumin is 27% +/- 5% (SD) (n = 6). This value of D(t)/D(free) is comparable to that for small solute sodium fluorescein (Stokes radius 0.45 nm), while p(alpha-lactalbumin) is only 3.4% of p(sodium fluorescein). Our results suggest that frog mesenteric tissue is much less selective to solutes than the microvessel wall. 相似文献
996.
Antioxidant activity of gallic acid from rose flowers in senescence accelerated mice 总被引:3,自引:0,他引:3
The activities of the antioxidant enzymes catalase (CAT) and glutathione peroxidase (GPx) in the blood and liver of the aging model induced by injection of different doses of D-gal into normal mice, and in senescence accelerated mice (SAM) of different ages, were determined. The results showed that the enzyme activities in the D-gal treated mice did not alter appreciably but the enzyme activities in blood of the SAM declined significantly with the increase in age, especially in the 9-month-old SAM. When gallic acid purified from rose flowers was used to treat the 9-month-old male SAM, it not only reinstated the activities of CAT and GPx but also significantly reduced the amount of malondialdehyde (MDA) in the liver, brain and kidney. The results demonstrated that 9-month-old male SAM represent an appropriate animal model to evaluate the antioxidant activities of natural products. 相似文献
997.
Tree root respiration utilizes a major portion of the primary production in forests and is an important process in the global carbon cycle. Because of the lack of ecologically relevant methods, tree root respiration in situ is much less studied compared with above-ground processes such as photosynthesis and leaf respiration. This study introduces a new (13)C natural tracer method for measuring tree root respiration in situ. The method partitions tree root respiration from soil respiration in buried root chambers. Rooting media substantially influenced root respiration rates. Measured in three media, the fine root respiration rates of longleaf pine were 0.78, 0.27 and 0.18 mg CO(2) carbon mg(-1) root nitrogen d(-1) at 25 degrees C in the native soil, tallgrass prairie soil, and sand-vermiculite mixture, respectively. Compared with the root excision method, the root respiration rate of longleaf pine measured by the field chamber method was 18% higher when using the native soil as rooting medium, was similar in the prairie soil, but was 42% lower if in the sand-vermiculite medium. This natural tracer method allows the use of an appropriate rooting medium and is capable of measuring root respiration nondestructively in natural forest conditions. 相似文献
998.
Sun JY Jing MY Weng XY Fu LJ Xu ZR Zi NT Wang JF 《Biological trace element research》2005,107(2):153-165
Zinc (Zn) is an essential nutrient that is required in humans and animals for many physiological functions, including immune
and antioxidant function, growth, and reproduction. The present study was performed to investigate the effects of three Zn
levels, including Zn adequate (35.94 mg/kg, as a control), Zn deficiency (3.15 mg/kg), and Zn overload (347.50 mg/kg) in growing
male rats for 6 wk. This allowed for evaluation of the effects that these Zn levels might have on body weight, organ weight,
enzymes activities, and tissues concentrations of Zn and Cu. The results showed that Zn deficiency has negative effects on
growth, organ weight, and biological parameters such as alkaline phosphatase (ALP) and Cu−Zn superoxide dismutase (Cu−Zn SOD)
activities, whereas Zn overload played an effective role in promoting growth, improving the developments of organs and enhancing
immune system. Hepatic metallothionein (MT) concentration showed an identical increase tendency in rats fed both Zn-deficient
and Zn-overload diets. The actual mechanism of reduction of Cu concentration of jejunum in rats fed a Zn-overload diet might
involve the modulation or inhibition of a Cu transporter protein by Zn and not by the induction of MT. 相似文献
999.
Global human genetics of HIV-1 infection and China 总被引:3,自引:0,他引:3
Genetic polymorphisms in human genes can influence the risk for HIV-1 infection and disease progression, although the reported effects of these alleles have been inconsistent. This review highlights the recent discoveries on global and Chinese genetic polymorphisms and their association with HIV-1 transmission and disease progression. 相似文献
1000.
Zheng?Fu Rong?Lu Guoli?Li Lan?Zhao Weizhen?Gao Xuchun?Che Xu?Jian Chunlei?Zhou Zhi?YaoEmail author 《中国科学C辑(英文版)》2005,48(5):523-530
This study aimed to observe the effects of tyroserleutide (tyrosyl-seryl-leucine, YSL) on the growth of human hepatocarcinoma
BEL-7402 that was transplanted into nude mice, and explore its anti-tumor mechanism preliminarily. YSL, at doses of 80 μg-kg-1 · d-1, 160 μg·kg-1 ·d-1 and 320 μg · kg-1 · d-1 significantly inhibited the growth of the human hepatocarcinoma BEL-7402 tumor in nude mice, producing inhibition of 21.66%,
41.34%, and 34.78%, respectively. Ultra structure of BEL-7402 tumor in nude mice showed that YSL could induce tumor cells
apoptosis and necrosis, cell organelle mitochondria and endoplasmic reticulum damage, and calcium overload. By confocal laser
scanning microscopy and flow cytometry, we found that 10 μg/mL YSL rapidly induced an increase of the concentration of cytoplasmic
free calcium in BEL-7402 cells in vitro, and maintained high concentrations of cytoplasmic free calcium for 1 h. Then the calcium concentration began to decrease
after 2 h, and was lower than that of the control group at 4 h and 24 h (P< 0.05). YSL also decreased the mitochondrial transmembrane potential of BEL-7402 cells in vitro, but had no effect on the calcium homeostasis or mitochondrial transmembrane potential of Chang liver hepatocytes. So affecting
calcium homeostasis, then inducing apoptosis and necrosis may be a mechanism by which YSL inhibits the tumor growth in animal
model. 相似文献