| 12853948 |
The DNA sequence of human chromosome 7. |
10.1038/nature01782 |
Nature |
The DNA sequence of human chromosome 7.
Abstract
- Human chromosome 7 has historically received prominent attention in the human genetics community, primarily related to the search for the cystic fibrosis gene and the frequent cytogenetic changes associated with various forms of cancer. Here we present more than 153 million base pairs representing 99.4% of the euchromatic sequence of chromosome 7, the first metacentric chromosome completed so far. The sequence has excellent concordance with previously established physical and genetic maps, and it exhibits an unusual amount of segmentally duplicated sequence (8.2%), with marked differences between the two arms. Our initial analyses have identified 1,150 protein-coding genes, 605 of which have been confirmed by complementary DNA sequences, and an additional 941 pseudogenes. Of genes confirmed by transcript sequences, some are polymorphic for mutations that disrupt the reading frame.
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| 12862462 |
Total synthesis of apratoxin A |
10.1021/ja036050w. |
J Am Chem Soc |
Total synthesis of apratoxin A
Abstract
- Apratoxin A, a cyclodepsipeptide isolated from cyanobacterial Lyngbya spp, has been synthesized. The total synthesis features stereocontrolled access to the novel polyketide and the late-stage installation of the sensitive 2,4-disubstituted thiazoline moiety using an intramolecular Staudinger reduction/aza-Wittig process.
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| 12872120 |
Binding of the Drosophila cytokine Spätzle to Toll is direct and establishes signaling |
10.1038/ni955. |
Nat Immunol |
Binding of the Drosophila cytokine Spätzle to Toll is direct and establishes signaling
Abstract
- The extracellular protein Spätzle is required for activation of the Toll signaling pathway in the embryonic development and innate immune defense of Drosophila. Spätzle is synthesized as a pro-protein and is processed to a functional form by a serine protease. We show here that the mature form of Spätzle triggers a Toll-dependent immune response after injection into the hemolymph of flies. Spätzle specifically bound to Drosophila cells and to Cos-7 cells expressing Toll. Furthermore, in vitro experiments showed that the mature form of Spätzle bound to the Toll ectodomain with high affinity and with a stoichiometry of one Spätzle dimer to two receptors. The Spätzle pro-protein was inactive in all these assays, indicating that the pro-domain sequence, which is natively unstructured, acts to prevent interaction of the cytokine and its receptor Toll. These results show that, in contrast to the human Toll-like receptors, Drosophila Toll requires only an endogenous protein ligand for activation and signaling.
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| 12873986 |
Identification and characterization of signal transducer and activator of transcription 3 recruitment sites within the epidermal growth factor receptor |
None |
Cancer Res |
Identification and characterization of signal transducer and activator of transcription 3 recruitment sites within the epidermal growth factor receptor
Abstract
- The oncogene signal transducer and activator of transcription 3 (Stat3) is constitutively activated in a wide variety of human cancers, including squamous cell carcinoma of the head and neck. In squamous cell carcinoma of the head and neck, Stat3 activation is mediated by up-regulation of the autocrine ligand-receptor pair, tumor growth factor alpha and epidermal growth factor receptor (EGFR), resulting in cell growth and resistance to apoptosis. The initiating molecular event in Stat3 activation is recruitment to specific phosphotyrosine motifs within signaling complexes. Stat3 activation by the EGFR has been mapped to the COOH-terminal region of the EGFR between amino acid residues 1061 and 1123, which contains Y1068 and Y1086. However, it is not known if Stat3 binds directly to the EGFR or if either of these tyrosines is involved in this interaction. In this study, we demonstrated in stably transfected NIH-3T3 cells that activation of Stat3 by EGFR was eliminated by mutation of all five EGFR tyrosines to phenylalanine and that activation was restored with return of two of the mutated tyrosine sites, Y1068 and Y1086, to wild-type. Stat3 was detected in the activated EGFR complex, and its presence within the complex was dependent on Y1068 and/or Y1086. Phosphododecapeptides spanning Y1068 and Y1086 were able to pull down Stat3 with Y1068 being more effective than Y1086 in this regard. Real-time mirror resonance affinity analysis revealed Stat3 bound to phosphododecapeptide Y1068 with a K(D) of 135 +/- 20 nM and to phosphododecapeptide Y1086 with a K(D) of 243 +/- 36 nM (P = 0.044), consistent with the results of the pull-down assays. The lower K(D) of Y1068 was completely attributable to slower dissociation of Stat3 bound to Y1068 versus Y1086. Each phosphododecapeptide was capable of destabilizing Stat3 homodimers in vitro. When delivered into squamous carcinoma cells, phosphopeptides spanning Y1068 and Y1086 were able to inhibit EGFR-stimulated Stat3 DNA binding activity and cell proliferation.
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| 12874677 |
Octreotide lowers gastric mucosal blood flow in normal and portal hypertensive stomachs |
10.1007/s00464-002-9274-z. |
Surg Endosc |
Octreotide lowers gastric mucosal blood flow in normal and portal hypertensive stomachs
Abstract
- The vasoactive peptide octreotide has an established role in controlling variceal hemorrhage. The mechanism of action is believed to be a reduction in splanchnic blood flow. A decrease in splanchnic blood flow should be mirrored by a decrease in gastric mucosal blood flow (GMBF). Laser Doppler flowmetry (LDF) should detect changes in GMBF.
In seven normal volunteers and four patients with portal hypertension, 100 micro g of octreotide was administered as an intravenous bolus. Continuous LDF measurements were then made at a single point on the midantrum for at least 10 min and plotted against time for each subject.
After a variable period of stabilization, GMBF decreased in all subjects except one. This was statistically significant in both the controls and the patients with portal hypertension.
Octreotide decreases GMBF in normal and portal hypertensive stomachs. Laser Doppler is a useful and minimally invasive tool to assess the effect of drugs on GMBF.
|
| 12889883 |
The total synthesis and stereochemical revision of yanucamide A |
10.1021/ol034803d. |
Org Lett |
The total synthesis and stereochemical revision of yanucamide A
Abstract
- [reaction: see text] The first total synthesis of yanucamide A is reported via amide and ester couplings of the key components. This synthesis has established the configuration at the previously ambiguous 3-position, and also revised the stereochemistry at the 22-position, to give 3S,12S,17S,22S for the natural product.
|
| 12900418 |
Solution conformation of alphaA-conotoxin EIVA, a potent neuromuscular nicotinic acetylcholine receptor antagonist from Conus ermineus |
10.1074/jbc.M303342200. |
J Biol Chem |
Solution conformation of alphaA-conotoxin EIVA, a potent neuromuscular nicotinic acetylcholine receptor antagonist from Conus ermineus
Abstract
- We report the solution three-dimensional structure of an alphaA-conotoxin EIVA determined by nuclear magnetic resonance spectroscopy and restrained molecular dynamics. The alphaA-conotoxin EIVA consists of 30 amino acids representing the largest peptide among the alpha/alphaA-family conotoxins discovered so far and targets the neuromuscular nicotinic acetylcholine receptor with high affinity. alphaA-Conotoxin EIVA consists of three distinct structural domains. The first domain is mainly composed of the Cys3-Cys11-disulfide loop and is structurally ill-defined with a large backbone root mean square deviation of 1.91 A. The second domain formed by residues His12-Hyp21 is extremely well defined with a backbone root mean square deviation of 0.52 A, thus forming a sturdy stem for the entire molecule. The third C-terminal domain formed by residues Hyp22-Gly29 shows an intermediate structural order having a backbone root mean square deviation of 1.04 A. A structurally ill-defined N-terminal first loop domain connected to a rigid central molecular stem seems to be the general structural feature of the alphaA-conotoxin subfamily. A detailed structural comparison between alphaA-conotoxin EIVA and alphaA-conotoxin PIVA suggests that the higher receptor affinity of alphaA-conotoxin EIVA than alphaA-conotoxin PIVA might originate from different steric disposition and charge distribution in the second loop "handle" motif.
|
| 12913315 |
Identification of the lantibiotic nisin Q, a new natural nisin variant produced by Lactococcus lactis 61-14 isolated from a river in Japan |
10.1271/bbb.67.1616. |
Biosci Biotechnol Biochem |
Identification of the lantibiotic nisin Q, a new natural nisin variant produced by Lactococcus lactis 61-14 isolated from a river in Japan
Abstract
- Lactococcus lactis 61-14 isolated from river water produced a bacteriocin active against a wide range of Gram-positive bacteria. N-terminal amino acid sequencing, mass spectral analysis of the purified bacteriocin, and genetic analysis using nisin-specific primers showed that the bacteriocin was a new natural nisin variant, termed nisin Q. Nisin Q and nisin A differ in four amino acids in the mature peptide and two in the leader sequence.
|
| 12915402 |
MrgX2 is a high potency cortistatin receptor expressed in dorsal root ganglion |
10.1074/jbc.M302456200. |
J Biol Chem |
MrgX2 is a high potency cortistatin receptor expressed in dorsal root ganglion
Abstract
- MrgX2 is a recently identified orphan G-protein-coupled receptor whose ligand and physiological function were unknown. Here we describe cortistatin, a neuropeptide for which no specific receptor has been identified previously, as a high potency ligand at MrgX2. Cortistatin has several biological functions including roles in sleep regulation, locomotor activity, and cortical function. Using a "reverse pharmacology" approach, we have identified a number of additional cyclic peptide agonists for MrgX2, determined their rank order of potency, and demonstrated that this receptor has a pharmacological profile distinct from the other characterized members of the Mrg (Mas-related genes) family. In MrgX2-expressing cells, cortistatin-stimulated increases in intracellular Ca2+ but had no effect on basal or forskolin-stimulated cAMP levels, suggesting that this receptor is Gq-coupled. Immunohistochemical and quantitative PCR studies show MrgX2 to have a limited expression profile, both peripheral and within the central nervous system, with highest levels in dorsal root ganglion.
|
| 12915623 |
Delayed puberty and primary amenorrhea associated with a novel mutation of the human follicle-stimulating hormone receptor: clinical, histological, and molecular studies |
10.1210/jc.2003-030217. |
J Clin Endocrinol Metab |
Delayed puberty and primary amenorrhea associated with a novel mutation of the human follicle-stimulating hormone receptor: clinical, histological, and molecular studies
Abstract
- Inactivating mutations of the FSH receptor have been described in rare cases of premature ovarian failure. Only one mutation was associated with a complete phenotype, including delayed puberty, primary amenorrhea, and small ovaries. We describe here a new patient presenting a similar complete phenotype of premature ovarian failure, with high plasma FSH levels associated with very low estrogen and inhibin B levels. No biological response to high doses of recombinant FSH was detected. A novel homozygous Pro(519)Thr mutation was found in this patient. This mutation is located in the second extracellular loop of the FSH receptor, within a motif highly conserved in gonadotropin and TSH receptors. The mutation totally impairs adenylate cyclase stimulation in vitro. FSH binding experiments and confocal microscopy showed that this mutation alters the cell surface targeting of the mutated receptor, which remains trapped intracellularly. Histological studies of the ovaries of the patient showed an increase in the density of small follicles compared with age-matched normal women. A complete block in follicular maturation after the primary stage was also observed. Immunocytochemical studies allowed detection of the expression of c-Kit and proliferation cellular nuclear antigen, whereas no apoptosis was shown by the 3'-end-labeling method. This observation supports the concept that in humans FSH seems mandatory for the initiation of follicular growth only after the primary stage. In our patient complete FSH resistance yields infertility, which is remarkably associated with the persistence of a high number of small follicles.
|
| 12925710 |
EphB1 recruits c-Src and p52Shc to activate MAPK/ERK and promote chemotaxis |
10.1083/jcb.200302073. |
J Cell Biol |
EphB1 recruits c-Src and p52Shc to activate MAPK/ERK and promote chemotaxis
Abstract
- Eph receptors and their ligands (ephrins) play an important role in axonal guidance, topographic mapping, and angiogenesis. The signaling pathways mediating these activities are starting to emerge and are highly cell- and receptor-type specific. Here we demonstrate that activated EphB1 recruits the adaptor proteins Grb2 and p52Shc and promotes p52Shc and c-Src tyrosine phosphorylation as well as MAPK/extracellular signal-regulated kinase (ERK) activation. EphB1-mediated increase of cell migration was abrogated by the MEK inhibitor PD98059 and Src inhibitor PP2. In contrast, cell adhesion, which we previously showed to be c-jun NH2-terminal kinase (JNK) dependent, was unaffected by ERK1/2 and Src inhibition. Expression of dominant-negative c-Src significantly reduced EphB1-dependent ERK1/2 activation and chemotaxis. Site-directed mutagenesis experiments demonstrate that tyrosines 600 and 778 of EphB1 are required for its interaction with c-Src and p52Shc. Furthermore, phosphorylation of p52Shc by c-Src is essential for its recruitment to EphB1 signaling complexes through its phosphotyrosine binding domain. Together these findings highlight a new aspect of EphB1 signaling, whereby the concerted action of c-Src and p52Shc activates MAPK/ERK and regulates events involved in cell motility.
|
| 12930927 |
A chorionic gonadotropin-sensitive mutation in the follicle-stimulating hormone receptor as a cause of familial gestational spontaneous ovarian hyperstimulation syndrome |
10.1056/NEJMoa030065. |
N Engl J Med |
A chorionic gonadotropin-sensitive mutation in the follicle-stimulating hormone receptor as a cause of familial gestational spontaneous ovarian hyperstimulation syndrome
Abstract
|
| 12930928 |
Ovarian hyperstimulation syndrome due to a mutation in the follicle-stimulating hormone receptor |
10.1056/NEJMoa030064. |
N Engl J Med |
Ovarian hyperstimulation syndrome due to a mutation in the follicle-stimulating hormone receptor
Abstract
|
| 12936980 |
Deciphering tuberactinomycin biosynthesis: isolation, sequencing, and annotation of the viomycin biosynthetic gene cluster |
10.1128/AAC.47.9.2823-2830.2003. |
Antimicrob Agents Chemother |
Deciphering tuberactinomycin biosynthesis: isolation, sequencing, and annotation of the viomycin biosynthetic gene cluster
Abstract
- The tuberactinomycin antibiotics are essential components in the drug arsenal against Mycobacterium tuberculosis infections and are specifically used for the treatment of multidrug-resistant tuberculosis. These antibiotics are also being investigated for their targeting of the catalytic RNAs involved in viral replication and for the treatment of bacterial infections caused by methicillin-resistant Staphylococcus aureus strains and vancomycin-resistant enterococci. We report on the isolation, sequencing, and annotation of the biosynthetic gene cluster for one member of this antibiotic family, viomycin, from Streptomyces sp. strain ATCC 11861. This is the first gene cluster for a member of the tuberactinomycin family of antibiotics sequenced, and the information gained can be extrapolated to all members of this family. The gene cluster covers 36.3 kb of DNA and encodes 20 open reading frames that we propose are involved in the biosynthesis, regulation, export, and activation of viomycin, in addition to self-resistance to the antibiotic. These results enable us to predict the metabolic logic of tuberactinomycin production and begin steps toward the combinatorial biosynthesis of these antibiotics to complement existing chemical modification techniques to produce novel tuberactinomycin derivatives.
|
| 12946412 |
Primary and 3-D modelled structures of two cyclotides from Viola odorata |
10.1016/s0031-9422(03)00218-8. |
Phytochemistry |
Primary and 3-D modelled structures of two cyclotides from Viola odorata
Abstract
- Two polypeptides named vodo M and vodo N, both of 29 amino acids, have been isolated from Viola odorata L. (Violaceae) using ion exchange chromatography and reversed phase HPLC. The sequences were determined by automated Edman degradation, quantitative amino acid analysis, and mass spectrometry (MS). Using MS, it was established that vodo M (cyclo-SWPVCTRNGAPICGESCFTGKCYTVQCSC) and vodo N (cyclo-SWPVCYRNGLPVCGETCTLGKCYTAGCSC) form a head-to-tail cyclic backbone and that six cysteine residues are involved in three disulphide bonds. Their origin, sequences, and cyclic nature suggest that these peptides belong to the family of cyclic plant peptides, called cyclotides. The three-dimensional structures of vodo M and vodo N were modelled by homology, using the experimentally determined structure of the cyclotide kalata B1 as the template. The images of vodo M and vodo N show amphipathic structures with considerable surface hydrophobicity for a protein modelled in a polar environment.
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