Molecular cloning of a gene sequence regulated by nerve growth factor

Nerve growth factor (NGF) is essential for the development and differentiation of sympathetic or sensory neurons. A complementary DNA was cloned that corresponds to a gene sequence induced more than 50-fold in a cultured target cell line of pheochromocytoma cells (PC12 cells) 5 hours after the addition of NGF. The induced messenger RNA encodes a 90,000-dalton polypeptide that may represent one of the primary events in NGF-induced differentiation of neurons.     

Evolution of shape by multiple regulatory changes to a growth gene

The genetic changes responsible for morphological differences between species are largely unidentified. Such changes can involve modifications of growth that are relevant to understanding evolution, development, and disease. We identified a gene that induces male-specific wing size and shape differences between Nasonia wasp species. Fine-scale mapping and in situ hybridization reveal that changes in at least three regions (two strictly in noncoding sequence) around the gene unpaired-like (upd-like) cause changes in spatial and temporal expression of upd-like in the developing wing and corresponding changes in wing width. Upd-like shows homology to the Drosophila unpaired gene, a well-studied signaling protein that regulates cell proliferation and differentiation. Our results indicate how multiple changes in the regulation of upd-like are involved in microevolution of morphological and sex-specific differences between species.     

A regulatory SNP causes a human genetic disease by creating a new transcriptional promoter

We describe a pathogenetic mechanism underlying a variant form of the inherited blood disorder alpha thalassemia. Association studies of affected individuals from Melanesia localized the disease trait to the telomeric region of human chromosome 16, which includes the alpha-globin gene cluster, but no molecular defects were detected by conventional approaches. After resequencing and using a combination of chromatin immunoprecipitation and expression analysis on a tiled oligonucleotide array, we identified a gain-of-function regulatory single-nucleotide polymorphism (rSNP) in a nongenic region between the alpha-globin genes and their upstream regulatory elements. The rSNP creates a new promoterlike element that interferes with normal activation of all downstream alpha-like globin genes. Thus, our work illustrates a strategy for distinguishing between neutral and functionally important rSNPs, and it also identifies a pathogenetic mechanism that could potentially underlie other genetic diseases.     

A gene regulatory network subcircuit drives a dynamic pattern of gene expression

Early specification of endomesodermal territories in the sea urchin embryo depends on a moving torus of regulatory gene expression. We show how this dynamic patterning function is encoded in a gene regulatory network (GRN) subcircuit that includes the otx, wnt8, and blimp1 genes, the cis-regulatory control systems of which have all been experimentally defined. A cis-regulatory reconstruction experiment revealed that blimp1 autorepression accounts for progressive extinction of expression in the center of the torus, whereas its outward expansion follows reception of the Wnt8 ligand by adjacent cells. GRN circuitry thus controls not only static spatial assignment in development but also dynamic regulatory patterning.     

神经生长因子对兔下颌骨骨折愈合的影响

目的 探讨神经生长因子(NGF)对下颌骨骨折愈合的作用.方法 30只白兔随机分为NGF组和对照组,每组15只;制作右下颌骨骨折模型,立即行钛夹板固定.实验组行NGF 0.4μg/d局部注射,对照组用生理盐水替代.术后第7、14、28天处死,切取下颌骨,利用骨密度仪和钼靶X-测量骨折处骨痂密度和灰度,骨组织切片作形态计量...     

The trk proto-oncogene product: a signal transducing receptor for nerve growth factor.

The trk proto-oncogene encodes a 140-kilodalton, membrane-spanning protein tyrosine kinase (p140prototrk) that is expressed only in neural tissues. Nerve growth factor (NGF) stimulates phosphorylation of p140prototrk in neural cell lines and in embryonic dorsal root ganglia. Affinity cross-linking and equilibrium binding experiments with 125I-labeled NGF indicate that p140prototrk binds NGF specifically in cultured cells with a dissociation constant of 10(-9) molar. The identification of p140prototrk as an NGF receptor indicates that this protein participates in the primary signal transduction mechanism of NGF.     

A yeast gene that is essential for release from glucose repression encodes a protein kinase

The SNF1 gene plays a central role in carbon catabolite repression in the yeast Saccharomyces cerevisiae, namely that SNF1 function is required for expression of glucose-repressible genes. The nucleotide sequence of the cloned SNF1 gene was determined, and the predicted amino acid sequence shows that SNF1 encodes a 72,040-dalton polypeptide that has significant homology to the conserved catalytic domain of mammalian protein kinases. Specific antisera were prepared and used to identify the SNF1 protein. The protein was shown to transfer phosphate from adenosine triphosphate to serine and threonine residues in an in vitro autophosphorylation reaction. These findings indicate that SNF1 encodes a protein kinase and suggest that protein phosphorylation plays a critical role in regulation by carbon catabolite repression in eukaryotic cells.     

Regeneration in spinal neurons: proteosynthesis following nerve growth factor administration

Incorporation of H(3)-leucine into dorsal root ganglion cells in rats was markedly increased over that of controls following section of sciatic and femoral nerves. Crush lesion of dorsal roots did not increase the H(3)-leucine uptake of these cells except in animals which had received nerve growth factor after the operation.     

A cell-cycle constraint on the regulation of gene expression by platelet-derived growth factor

In density-arrested monolayer cultures of Balb/c 3T3 cells, platelet-derived growth factor (PDGF) stimulates expression of the c-myc and c-fos proto-oncogenes, as well as the functionally uncharacterized genes, JE, KC, and JB. These genes are not coordinately regulated. Under ordinary conditions, c-fos, JE, KC, and JB respond to PDGF only when the cells are in a state of G0 growth arrest at the time of PDGF addition. The c-myc gene is regulated in opposition to the other genes, responding best to PDGF in cycling cultures.     

The obesity-associated FTO gene encodes a 2-oxoglutarate-dependent nucleic acid demethylase

Variants in the FTO (fat mass and obesity associated) gene are associated with increased body mass index in humans. Here, we show by bioinformatics analysis that FTO shares sequence motifs with Fe(II)- and 2-oxoglutarate-dependent oxygenases. We find that recombinant murine Fto catalyzes the Fe(II)- and 2OG-dependent demethylation of 3-methylthymine in single-stranded DNA, with concomitant production of succinate, formaldehyde, and carbon dioxide. Consistent with a potential role in nucleic acid demethylation, Fto localizes to the nucleus in transfected cells. Studies of wild-type mice indicate that Fto messenger RNA (mRNA) is most abundant in the brain, particularly in hypothalamic nuclei governing energy balance, and that Fto mRNA levels in the arcuate nucleus are regulated by feeding and fasting. Studies can now be directed toward determining the physiologically relevant FTO substrate and how nucleic acid methylation status is linked to increased fat mass.     

The yeast cell cycle gene CDC34 encodes a ubiquitin-conjugating enzyme

Mutants in the gene CDC34 of the yeast Saccharomyces cerevisiae are defective in the transition from G1 to the S phase of the cell cycle. This gene was cloned and shown to encode a 295-residue protein that has substantial sequence similarity to the product of the yeast RAD6 gene. The RAD6 gene is required for a variety of cellular functions including DNA repair and was recently shown to encode a ubiquitin-conjugating enzyme. When produced in Escherichia coli, the CDC34 gene product catalyzed the covalent attachment of ubiquitin to histones H2A and H2B in vitro, demonstrating that the CDC34 protein is another distinct member of the family of ubiquitin-conjugating enzymes. The cell cycle function of CDC34 is thus likely to be mediated by the ubiquitin-conjugating activity of its product.     

Silicon: a possible factor in bone calcification

Silicon, a relatively unknown trace element in nutritional research, has been uniquely localized in active calcification sites in young bone. Silicon increases directly with calcium at relatively low calcium concentrations and falls below the detection limit at compositions approaching hydroxyapatite. It is suggested that silicon is associated with calcium in an early stage of calcification.     

神经生长因子诱导PC12细胞对细胞周期的影响

目的:观察神经生长因子(NGF)诱导PC 12细胞周期的变化,以建立体外神经元样细胞周期的研究模型。方法:用流式细胞仪检测不同质量浓度NGF诱导及50μg/L NGF诱导不同天数PC 12细胞的细胞周期。结果:(1)不同质量浓度NGF诱导PC 12细胞7d,细胞百分比G0/G1期升高,S和G2/M期降低,25,50,100μg/L NGF诱导组与阴性对照组,50与25,100μg/L NGF诱导组比较,差异有显著性(P<0.01或P<0.05);(2)50μg/L NGF诱导PC 12细胞不同天数的细胞百分比,G0/G1期从诱导第1天始升高,至7d达到最高,9d又有下降,S期从诱导第1天开始降低,至7d最低,9d又有上升,诱导1,3,5,7,9d与基础组比较,差异有显著性(P<0.05或P<0.01);G2/M期从诱导3d降低,至7d降至最低,9d又有升高,诱导3,5,7,9d与基础组比较,P<0.01。G0/G1期、S期、G2/M期细胞百分比,诱导9d与诱导7d比较,差异有显著性(P均<0.01)。结论:未经NGF诱导的PC 12细胞具有有丝分裂能力,经NGF诱导的PC 12细胞逐渐减少增殖,大部分细胞停滞在G0/G1期,趋向于神经元样分化,50μg/L NGF诱导7d的PC 12细胞可用于神经元样细胞周期模型的实验研究。