排序方式: 共有21条查询结果,搜索用时 31 毫秒
1.
Down-regulation of human<Emphasis Type="Italic">NDR</Emphasis> gene in megakaryocytic differentiation of erythroleukemia K562 cells 总被引:2,自引:0,他引:2
To study the control of hematopoietic cell differentiation, a human negative differentiation regulator (NDR) gene was identified by the comparative analysis of differentially expressed genes in hemato-lymphoid tissues.NDR is expressed preferentially in the adult bone marrow, fetal liver and testis. Immunocytochemistry with anti-NDR antiserum showed the presence of NDR in human erythroleukemia K562 cell line and CD34+ cells sorted from the umbilical cord blood. When fused to the green fluorescent protein (GFP), NDR was directed to the nucleus of mouse 3T3 and K562 cells. Fusion protein with a deletion from residues 7 to 87 was detected in the cytoplasm. NDR appeared not to affect the proliferation of K562 cells when overly expressed. However, its expression was down-regulated during megakaryocytic differentiation of K562 cells induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). Down-regulation of NDR correlated well with up-regulation of megakaryocytic markers, CD41 and CD61. Overexpression of the nuclear NDR-GFP in K562 cells inhibited the expression of CD41 and CD61 in megakaryocytic differentiation. Treatment of K562 cells with GF-109203X (GFX), an antagonist of the protein kinase C (PKC), blocked NDR down-regulation, up-regulated expression of CD41/CD61 and TPA-induced megakaryocytic differentiation. These results suggest a novel function of nuclear NDR protein in regulating hematopoietic cell development. 相似文献
2.
TÜNDE TÓTH OTTÓ ZSIROS MIHÁLY KIS GYŐZŐ GARAB LÁSZLÓ KOVÁCS 《Plant, cell & environment》2012,35(12):2075-2086
Despite intense research, the mechanism of Cd2+ toxicity on photosynthesis is still elusive because of the multiplicity of the inhibitory effects and different barriers in plants. The quick Cd2+ uptake in Synechocystis PCC 6803 permits the direct interaction of cadmium with the photosynthetic machinery and allows the distinction between primary and secondary effects. We show that the CO2‐dependent electron transport is rapidly inhibited upon exposing the cells to 40 µm Cd2+ (50% inhibition in ~15 min). However, during this time we observe only symptoms of photosystem I acceptor side limitation and a build of an excitation pressure on the reaction centres, as indicated by light‐induced P700 redox transients, O2 polarography and changes in chlorophyll a fluorescence parameters. Inhibitory effects on photosystem II electron transport and the degradation of the reaction centre protein D1 can only be observed after several hours, and only in the light, as revealed by chlorophyll a fluorescence transients, thermoluminescence and immunoblotting. Despite the marked differences in the manifestations of these short‐ and long‐term effects, they exhibit virtually the same Cd2+ concentration dependence. These data strongly suggest a cascade mechanism of the toxic effect, with a primary effect in the dark reactions. 相似文献
3.
PETER BOGNER DENYS N. WHEATLEY CSABA BORBLY ATTILA MISETA 《Cell biology international》1996,20(11):741-749
Exchange of erythrocyte intracellular (i/c) K+for extracellular (e/c) Na+in human erythrocytes treated with sub-CMC concentrations of the non-ionic detergent Brij 58 can be stopped by reincubation in serum or albumin containing solutions. The progressive equilibration of the K+contents of detergent-treated human erythrocytes with the incubation medium was reversed by an albumin-mediated withdrawal of detergent molecules from the cell. Re-establishment of near normal [K+] in terms of K+/kg water proceeds in two ways: (i) a metabolism-dependent net accumulation of K+ions; and (ii) a metabolism-independent shrinkage of erythrocytes, this being the more significant factor. 相似文献
4.
5.
18S rRNA data indicate that Aschelminthes are polyphyletic in origin and consist of at least three distinct clades 总被引:7,自引:1,他引:6
Winnepenninckx B; Backeljau T; Mackey LY; Brooks JM; De Wachter R; Kumar S; Garey JR 《Molecular biology and evolution》1995,12(6):1132-1137
The Aschelminthes is a collection of at least eight animal phyla,
historically grouped together because the absence of a true body cavity was
perceived as a pseudocoelom. Analyses of 18S rRNA sequences from six
Aschelminth phyla (including four previously unpublished sequences) support
polyphyly for the Aschelminthes. At least three distinct groups of
Aschelminthes were detected: the Priapulida among the protostomes, the
Rotifera-Acanthocephala as a sister group to the protostomes, and the
Nematoda as a basal group to the triploblastic Eumetazoa.
相似文献
6.
Chimpanzee fetal G gamma and A gamma globin gene nucleotide sequences provide further evidence of gene conversions in hominine evolution 总被引:5,自引:0,他引:5
The fetal globin genes G gamma and A gamma from one chromosome of a
chimpanzee (Pan troglodytes) were sequenced and found to be closely similar
to the corresponding genes of man and the gorilla. These genes contain
identical promoter and termination signals and have exons 1 and 2 separated
by the conserved short intron 1 (122 bp) and exons 2 and 3 separated by the
more rapidly evolving, larger intron 2 (893 bp and 887 bp in chimpanzee G
gamma and A gamma, respectively). Each intron 2 has a stretch of simple
sequence DNA (TG)n serving possibly as a "hot spot" for recombination. The
two chimpanzee genes encode polypeptide chains that differ only at position
136 (glycine in G gamma and alanine in A gamma) and that are identical to
the corresponding human chains, which have aspartic acid at position 73 and
lysine at 104 in contrast to glycine and arginine at these respective
positions of the gorilla A gamma chain. Phylogenetic analysis by the
parsimony method revealed four silent (synonymous) base substitutions in
evolutionary descent of the chimpanzee G gamma and A gamma codons and none
in the human and gorilla codons. These Homininae (Pan, Homo, Gorilla)
coding sequences evolved at one-tenth the average mammalian rate for
nonsynonymous and one-fourth that for synonymous substitutions. Three
sequence regions that were affected by gene conversions between chimpanzee
G gamma and A gamma loci were identified: one extended 3' of the hot spot
with G gamma replaced by the A gamma sequence, another extended 5' of the
hot spot with A gamma replaced by G gamma, and the third conversion
extended from the 5' flanking to the 5' end of intron 2, with G gamma
replaced here by the A gamma sequence. A conversion similar to this third
one has occurred independently in the descent of the gorilla genes. The
four previously identified conversions, labeled C1-C4 (Scott et al. 1984),
were substantiated with the addition of the chimpanzee genes to our
analysis (C1 being shared by all three hominines and C2, C3, and C4 being
found only in humans). Thus, the fetal genes from all three of these
hominine species have been active in gene conversions during the descent of
each species.
相似文献
7.
8.
Ch'ang HJ Maj JG Paris F Xing HR Zhang J Truman JP Cardon-Cardo C Haimovitz-Friedman A Kolesnick R Fuks Z 《Nature medicine》2005,11(5):484-490
Although stem cells succumbing to reproductive death are assumed to be the single relevant targets in radiation tissue damage, recent studies showed intestinal stem cell damage is conditionally linked to crypt endothelial apoptosis, defining a two-target model. Here we report that when mouse intestines were protected against microvascular apoptosis, radiation switched as the dose escalated to a previously unrecognized crypt stem cell target, activating ceramide synthase-mediated apoptosis to initiate intestinal damage. Whereas ataxia telangiectasia-mutated (ATM) kinase normally represses ceramide synthase, its derepression in Atm(-/-) mice increased crypt stem cell radiosensitivity 3.7-fold without sensitizing the microvascular response. Discovery of this intestinal radiosensitivity mechanism allowed design of an antisense Atm oligonucleotide treatment which phenocopied the Atm(-/-) mouse, reordering ceramide synthase-mediated stem cell death to become the first-line gastrointestinal response of wild-type littermates. These experiments indicate that tissues operate multiple potential targets activated consecutively according to their inherent radiosensitivities that may be reordered therapeutically to control radiation tissue responses. 相似文献
9.
Ekwere T Ifon Alan LY Pang Warren Johnson Kathleen Cashman Sharon Zimmerman Sumitra Muralidhar Wai-Yee Chan John Casey Leonard Jason Rosenthal 《Cancer cell international》2005,5(1):19
Background
Insensitivity of advanced-stage prostate cancer to androgen ablation therapy is a serious problem in clinical practice because it is associated with aggressive progression and poor prognosis. Targeted therapeutic drug discovery efforts are thwarted by lack of adequate knowledge of gene(s) associated with prostate tumorigenesis. Therefore there is the need for studies to provide leads to targeted intervention measures. Here we propose that stable expression of U94, a tumor suppressor gene encoded by human herpesvirus 6A (HHV-6A), could alter gene expression and thereby inhibit the tumorigenicity of PC3 cell line. Microarray gene expression profiling on U94 recombinant PC3 cell line could reveal genes that would elucidate prostate cancer biology, and hopefully identify potential therapeutic targets. 相似文献10.