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Mel-18 is a mammalian homolog of Polycomb group (PcG) genes. Microarray analysis revealed that Mel-18 expression was induced during endothelial progenitor cell (EPC) differentiation and correlates with the expression of EC-specific protein markers. Overexpression of Mel-18 promoted EPC differentiation and angiogenic activity of ECs. Accordingly, silencing Mel-18 inhibited EC migration and tube formation in vitro. Gene expression profiling showed that Mel-18 regulates angiogenic genes including kinase insert domain receptor (KDR), claudin 5, and angiopoietin-like 2. Our findings demonstrate, for the first time, that Mel-18 plays a significant role in the angiogenic function of ECs by regulating endothelial gene expression.  相似文献   

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Polycomb group (PcG) proteins play a role in the maintenance of cellular identity throughout many rounds of cell division through the regulation of gene expression. In this report we demonstrate that the loss of the PcG gene mel-18 impairs the expansion of the most immature T progenitor cells at a stage before the rearrangement of the TCR beta-chain gene in vivo and in vitro. This impairment of these T progenitors appears to be associated with increased susceptibility to cell death. We also show that the expression of Hes-1, one of the target genes of the Notch signaling pathway, is drastically down-regulated in early T progenitors isolated from mel-18(-/-) mice. In addition, mel-18(-/-) T precursors could not maintain the Hes-1 expression induced by Delta-like-1 in monolayer culture. Collectively, these data indicate that mel-18 contributes to the maintenance of the active state of the Hes-1 gene as a cellular memory system, thereby supporting the expansion of early T progenitors.  相似文献   

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The yeast Sir2 gene encodes a protein (Sir2p) that plays an essential role in silencing regulation at mating-type loci, rDNA, and telomeres. Recent studies have also shown that the protein participates in cell cycle regulation, DNA double-strand break repair, meiotic checkpoint control, and histone deacetylation. Overexpression of wildtype Sir2p in yeast resulted in an extended life span but mutant Sir2p shortened the life span, suggesting its function in aging processes. Sir2p is evolutionarily conserved from prokaryotes to higher eukaryotes. However, its function(s) in mammals remains unknown. To investigate Sir2p function(s) in mice, we cloned and characterized two mouse Sir2-like genes. Our results revealed that the two mouse Sir2-like proteins (mSIR2L2 and mSIR2L3) are most similar to the human Sir2-like proteins SIR2L2 and SIR2L3, respectively. Sir2 core domains are highly conserved in the two proteins and yeast Sir2p; however, the intracellular localizations of both mSIR2L2 and mSIR2L3 differ from that of yeast Sir2p and from one another. The two mouse genes have completely different genomic structures but were mapped on the same chromosome. It seems that the two mouse proteins, though they have Sir2 conserved domains, may function differently than yeast Sir2p.  相似文献   

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A homologue of the ferric uptake regulator gene (fur) was isolated from Moraxella bovis by degenerate polymerase chain reaction and cloning. Fur protein of M. bovis exhibited 72.1% amino acid identity with Acinetobacter calcoaceticus Fur. Western blot analysis showed a decrease of Fur expression in response to sufficient-iron conditions compared with deficient-iron conditions. An electrophoretic mobility-shift assay indicated that Fur protein binds to DNA fragments containing a putative Fur-box derived from the upstream region of the M. bovis fur gene. Fur of M. bovis may regulate the expression of iron transport systems in response to iron limitation in the environment.  相似文献   

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Cloning and characterization of the fur gene from Helicobacter pylori   总被引:1,自引:0,他引:1  
The fur homologue of Helicobacter pylori was isolated by screening a plasmid-based, genomic DNA library using the Fur titration assay (FURTA). The analysis of the DNA sequence revealed significant homology with Fur proteins from various other bacterial species. The highest degree of homology was observed for the Fur protein from Campylobacter jejuni. The H. pylori fur gene on a plasmid could partially complement the fur mutation in Escherichia coli strain H1681. The repressor activity depended on addition of iron to the medium indicating that iron acts as a co-repressor for the H. pylori protein similar to Fur from other bacteria. Comparison of Fur from H. pylori strain NCTC11638 with the recently published genomic DNA sequence of another strain (26695) confirmed the identity of the fur homologue and revealed that the fur locus is highly conserved in both strains.  相似文献   

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Two flavohemoglobin (FHb) genes, fhb1 and fhb2, were cloned from Aspergillus oryzae. The amino acid sequences of the deduced FHb1 and FHb2 showed high identity to other FHbs except for the predicted mitochondrial targeting signal in the N-terminus of FHb2. The recombinant proteins displayed absorption spectra similar to those of other FHbs. FHb1 and FHb2 were estimated to be a monomer and a dimer in solution, respectively. Both of the isozymes exhibit high NO dioxygenase (NOD) activity. FHb1 utilizes either NADH or NADPH as an electron donor, whereas FHb2 can only use NADH. These results suggest that FHb1 and FHb2 are fungal counterparts of bacterial FHbs and act as NO detoxification enzymes in the cytosol and mitochondria, respectively. This study is the first to show that a microorganism contains two isozymes of FHb and that intracellular localization of the isozymes could differ.  相似文献   

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The gene coding for the flavodoxin protein from Desulfovibrio desulfuricans [Essex 6] (ATCC 29577) has been cloned and sequenced. The gene was identified on Southern blots of HindIII-digested genomic DNA by hybridization to the coding region for the flavodoxin from Desulfovibrio vulgaris [Hildenborough] (Krey, G.D., Vanin, E.F. and Swenson, R.P. (1988) J. Biol. Chem. 263, 15436-15443). Ultimately, a 1.8 kb TaqI fragment was cloned which contains an open reading frame of 447 nucleotides coding for an acidic protein of 148 amino acids and calculated molecular weight of 15,726. The derived amino acid sequence of this protein is 47% identical to the flavodoxin from D. vulgaris. Regions of the polypeptide which form the flavin mononucleotide binding site are largely homologous; however, some perhaps significant differences are noted. The aromatic amino acid residues that flank the flavin isoalloxazine ring in the D. vulgaris structure, i.e., tryptophan-60 and tyrosine-98, are conserved in this flavodoxin.  相似文献   

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This report describes the cloning and characterization of a pseudouridine (psi) synthase from mouse that we have named mouse pseudouridine synthase 1 (mpus1p). The cDNA is approximately 1.5 kb and when used as a probe on a Northern blot of mouse RNA from tissues and cultured cells, several bands were detected. The open reading frame is 393 amino acids and has 35% identity over its length with yeast psi synthase 1 (pus1p). The recombinant protein was expressed in Escherichia coli and the purified protein converted specific uridines to psi in a number of tRNA substrates. The positions modified in stoichiometric amounts in vitro were 27/28 in the anticodon stem and also positions 34 and 36 in the anticodon of an intron containing tRNA. A human cDNA was also cloned and the smaller open reading frame (348 amino acids) was 92% identical over its length with mpus1p but is shorter by 45 amino acids at the amino terminus. The expressed recombinant human protein has no activity on any of the tRNA substrates, most probably the result of the truncated open reading frame.  相似文献   

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Based on the sequence of an expressed sequence tag, the full-length cDNA of 1,008 nucleotides was cloned from Ammopiptanthus mongolicus by rapid amplification of cDNA ends. It was designated as AmDHN, encoding a protein of 183 amino acids. The calculated molecular weight of the AmDHN protein is 18.4 k Da, and theoretical isoelectric point is 5.78. The AmDHN localized in nucleus. Under normal growth conditions, differential expression of AmDHN exhibited that the expression was the highest in seeds and the lowest in flowers. AmDHN could be induced by NaCl, PEG6000, ABA and drought treatments. Salt and drought resistances of transgenic plants with overexpression of AmDHN are improved. Taken together, these results demonstrated that AmDHN could regulate the expression of abiotic-responsive genes and plays important roles in modulating the tolerance of plants to abiotic stresses.  相似文献   

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Rab GTPase proteins are a kind of small GTP-binding proteins, which functions mainly focus on regulating interacellular trafficking pathways during vesicular transport. To date, 60 distinct human RAB proteins have been identified. RAB18 gene is discovered from endothelial cells. Its function is considered as endosomes and plasma membrane recycling. Research indicates RAB18 may relate to inflammation and some kinds of tumor. Here we report a splice variant of RAB18, which is 2571 bp in length and has an open reading frame coding a predicted 235 amino-acids protein. RT-PCR shows that the cDNA has different expression pattern with RAB18 and is highly expressed in testis.  相似文献   

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