| 23188045 |
Phenotypic variant of Brachydactyly-mental retardation syndrome in a family with an inherited interstitial 2q37.3 microdeletion including HDAC4. |
10.1038/ejhg.2012.240 |
Eur. J. Hum. Genet. |
Phenotypic variant of Brachydactyly-mental retardation syndrome in a family with an inherited interstitial 2q37.3 microdeletion including HDAC4.
Abstract
- Deletions of the chromosomal region 2q37 cause brachydactyly-mental retardation syndrome (BDMR), also known as Albright hereditary osteodystrophy-like syndrome. Recently, histone deacetylase 4 (HDAC4) haploinsufficiency has been postulated to be the critical genetic mechanism responsible for the main clinical characteristics of the BDMR syndrome like developmental delay and behavioural abnormalities in combination with brachydactyly type E (BDE). We report here on the first three generation familial case of BDMR syndrome with inheritance of an interstitial microdeletion of chromosome 2q37.3. The deletion was detected by array comparative genomic hybridization and comprises the HDAC4 gene and two other genes. The patients of this pedigree show a variable severity of psychomotor and behavioural abnormalities in combination with a specific facial dysmorphism but without BDE. Given that only about half of the patients with 2q37 deletions have BDE; we compared our patients with other patients carrying 2q37.3 deletions or HDAC4 mutations known from the literature to discuss the diagnostic relevance of the facial dysmorphism pattern in 2q37.3 deletion cases involving the HDAC4 gene. We conclude that HDAC4 haploinsufficiency is responsible for psychomotor and behavioural abnormalities in combination with the BDMR syndrome-specific facial dysmorphism pattern and that these clinical features have a central diagnostic relevance.
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| 23195955 |
Discovery of linear cyclotides in monocot plant Panicum laxum of Poaceae family provides new insights into evolution and distribution of cyclotides in plants |
10.1074/jbc.M112.415356. |
J Biol Chem |
Discovery of linear cyclotides in monocot plant Panicum laxum of Poaceae family provides new insights into evolution and distribution of cyclotides in plants
Abstract
- Cyclotides are disulfide-rich macrocyclic peptides that display a wide range of bioactivities and represent an important group of plant defense peptide biologics. A few linear variants of cyclotides have recently been identified. They share a high sequence homology with cyclotides but are biosynthetically unable to cyclize from their precursors. All hitherto reported cyclotides and their acyclic variants were isolated from dicot plants of the Rubiaceae, Violaceae, Cucurbitaceae, and recently the Fabaceae and Solanaceae families. Although several cyclotide-like genes in the Poaceae family were known from the data mining of the National Center for Biotechnology Information (NCBI) nucleotide database, their expression at the protein level has yet to be proven. Here, we report the discovery and characterization of nine novel linear cyclotides, designated as panitides L1-9, from the Panicum laxum of the Poaceae family and provide the first evidence of linear cyclotides at the protein level in a monocot plant. Disulfide mapping of panitide L3 showed that it possesses a cystine knot arrangement similar to cyclotides. Several panitides were shown to be active against Escherichia coli and cytotoxic to HeLa cells. They also displayed a high stability against heat and proteolytic degradation. Oxidative folding of the disulfide-reduced panitide L1 showed that it can fold efficiently into its native form. The presence of linear cyclotides in both dicots and monocots suggests their ancient origin and existence before the divergence of these two groups of flowering plants. Moreover, the Poaceae family contains many important food crops, and our discovery may open up new avenues of research using cyclotides and their acyclic variants in crop protection.
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| 23208736 |
How thiostrepton was made in the laboratory |
10.1002/anie.201205576. |
Angew Chem Int Ed Engl |
How thiostrepton was made in the laboratory
Abstract
- Thiostrepton, a powerful antibiotic belonging to the thiopeptide class, was synthesized in the laboratory for the first time in 2004 through an arduous campaign involving novel strategies and tactics, scenic detours, and unexpected roadblocks. In this Review the author narrates the long journey to success, not so dissimilar to Odysseus' return voyage to Ithaca, full of adventure, knowledge, and wisdom.
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| 23248299 |
Accurate prediction of secondary metabolite gene clusters in filamentous fungi |
10.1073/pnas.1205532110. |
Proc Natl Acad Sci U S A |
Accurate prediction of secondary metabolite gene clusters in filamentous fungi
Abstract
- Biosynthetic pathways of secondary metabolites from fungi are currently subject to an intense effort to elucidate the genetic basis for these compounds due to their large potential within pharmaceutics and synthetic biochemistry. The preferred method is methodical gene deletions to identify supporting enzymes for key synthases one cluster at a time. In this study, we design and apply a DNA expression array for Aspergillus nidulans in combination with legacy data to form a comprehensive gene expression compendium. We apply a guilt-by-association-based analysis to predict the extent of the biosynthetic clusters for the 58 synthases active in our set of experimental conditions. A comparison with legacy data shows the method to be accurate in 13 of 16 known clusters and nearly accurate for the remaining 3 clusters. Furthermore, we apply a data clustering approach, which identifies cross-chemistry between physically separate gene clusters (superclusters), and validate this both with legacy data and experimentally by prediction and verification of a supercluster consisting of the synthase AN1242 and the prenyltransferase AN11080, as well as identification of the product compound nidulanin A. We have used A. nidulans for our method development and validation due to the wealth of available biochemical data, but the method can be applied to any fungus with a sequenced and assembled genome, thus supporting further secondary metabolite pathway elucidation in the fungal kingdom.
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| 23269669 |
Site-specific N-linked glycosylation of receptor guanylyl cyclase C regulates ligand binding, ligand-mediated activation and interaction with vesicular integral membrane protein 36, VIP36. |
10.1074/jbc.m112.413906 |
J. Biol. Chem. |
Site-specific N-linked glycosylation of receptor guanylyl cyclase C regulates ligand binding, ligand-mediated activation and interaction with vesicular integral membrane protein 36, VIP36.
Abstract
- Guanylyl cyclase C (GC-C) is a multidomain, membrane-associated receptor guanylyl cyclase. GC-C is primarily expressed in the gastrointestinal tract, where it mediates fluid-ion homeostasis, intestinal inflammation, and cell proliferation in a cGMP-dependent manner, following activation by its ligands guanylin, uroguanylin, or the heat-stable enterotoxin peptide (ST). GC-C is also expressed in neurons, where it plays a role in satiation and attention deficiency/hyperactive behavior. GC-C is glycosylated in the extracellular domain, and differentially glycosylated forms that are resident in the endoplasmic reticulum (130 kDa) and the plasma membrane (145 kDa) bind the ST peptide with equal affinity. When glycosylation of human GC-C was prevented, either by pharmacological intervention or by mutation of all of the 10 predicted glycosylation sites, ST binding and surface localization was abolished. Systematic mutagenesis of each of the 10 sites of glycosylation in GC-C, either singly or in combination, identified two sites that were critical for ligand binding and two that regulated ST-mediated activation. We also show that GC-C is the first identified receptor client of the lectin chaperone vesicular integral membrane protein, VIP36. Interaction with VIP36 is dependent on glycosylation at the same sites that allow GC-C to fold and bind ligand. Because glycosylation of proteins is altered in many diseases and in a tissue-dependent manner, the activity and/or glycan-mediated interactions of GC-C may have a crucial role to play in its functions in different cell types.
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| 23281027 |
Structure of the O-glycosylated conopeptide CcTx from Conus consors venom |
10.1002/chem.201202713. |
Chemistry |
Structure of the O-glycosylated conopeptide CcTx from Conus consors venom
Abstract
- The glycopeptide CcTx, isolated from the venom of the piscivorous cone snail Conus consors, belongs to the κA-family of conopeptides. These toxins elicit excitotoxic responses in the prey by acting on voltage-gated sodium channels. The structure of CcTx, a first in the κA-family, has been determined by high-resolution NMR spectroscopy together with the analysis of its O-glycan at Ser7. A new type of glycopeptide O-glycan core structure, here registered as core type 9, containing two terminal L-galactose units {α-L-Galp-(1→4)-α-D-GlcpNAc-(1→6)-[α-L-Galp-(1→2)-β-D-Galp-(1→3)-]α-D-GalpNAc-(1→O)}, is highlighted. A sequence comparison to other putative members of the κA-family suggests that O-linked glycosylation might be more common than previously thought. This observation alone underlines the requirement for more careful and in-depth investigations into this type of post-translational modification in conotoxins.
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| 23299855 |
Des-acyl ghrelin analogs prevent high-fat-diet-induced dysregulation of glucose homeostasis |
10.1096/fj.12-221143. |
FASEB J |
Des-acyl ghrelin analogs prevent high-fat-diet-induced dysregulation of glucose homeostasis
Abstract
- There is clinical evidence that des-acyl ghrelin (DAG) favorably modulates glucose and lipid metabolism, although its mode of action is unknown. A murine model of prediabetes was used to assess possible mechanisms of action for DAG and a newly developed bioactive analog, AZP531. C57BL/6J mice were infused with saline, DAG, or AZP531 continuously for 4 wk, and fed either normal diet (ND) or normal diet for 2 wk followed by a high-fat diet (HFD) for 2 wk. Compared with mice in the ND group, HFD increased body and fat mass, caused glucose intolerance and insulin resistance, had proinflammatory effects in white adipose tissue, and caused lipid accumulation in brown adipose tissue. DAG and AZP531 treatment prevented HFD-induced proinflammatory effects, stimulated expression of mitochondrial function markers in brown adipose tissue, and prevented development of a prediabetic metabolic state. AZP531 also prevented a HFD-induced increase in acyl ghrelin levels. Our data indicate DAG analogs as potential treatment for the prevention of metabolic syndrome.
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| 23302862 |
How insulin engages its primary binding site on the insulin receptor |
10.1038/nature11781. |
Nature |
How insulin engages its primary binding site on the insulin receptor
Abstract
- Insulin receptor signalling has a central role in mammalian biology, regulating cellular metabolism, growth, division, differentiation and survival. Insulin resistance contributes to the pathogenesis of type 2 diabetes mellitus and the onset of Alzheimer's disease; aberrant signalling occurs in diverse cancers, exacerbated by cross-talk with the homologous type 1 insulin-like growth factor receptor (IGF1R). Despite more than three decades of investigation, the three-dimensional structure of the insulin-insulin receptor complex has proved elusive, confounded by the complexity of producing the receptor protein. Here we present the first view, to our knowledge, of the interaction of insulin with its primary binding site on the insulin receptor, on the basis of four crystal structures of insulin bound to truncated insulin receptor constructs. The direct interaction of insulin with the first leucine-rich-repeat domain (L1) of insulin receptor is seen to be sparse, the hormone instead engaging the insulin receptor carboxy-terminal α-chain (αCT) segment, which is itself remodelled on the face of L1 upon insulin binding. Contact between insulin and L1 is restricted to insulin B-chain residues. The αCT segment displaces the B-chain C-terminal β-strand away from the hormone core, revealing the mechanism of a long-proposed conformational switch in insulin upon receptor engagement. This mode of hormone-receptor recognition is novel within the broader family of receptor tyrosine kinases. We support these findings by photo-crosslinking data that place the suggested interactions into the context of the holoreceptor and by isothermal titration calorimetry data that dissect the hormone-insulin receptor interface. Together, our findings provide an explanation for a wealth of biochemical data from the insulin receptor and IGF1R systems relevant to the design of therapeutic insulin analogues.
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| 23313096 |
AP301, a synthetic peptide mimicking the lectin-like domain of TNF, enhances amiloride-sensitive Na(+) current in primary dog, pig and rat alveolar type II cells |
10.1016/j.pupt.2012.12.011. |
Pulm Pharmacol Ther |
AP301, a synthetic peptide mimicking the lectin-like domain of TNF, enhances amiloride-sensitive Na(+) current in primary dog, pig and rat alveolar type II cells
Abstract
- Pulmonary permeability oedema is a frequent complication in a number of life-threatening lung conditions, such as ALI and ARDS. Apart from ventilation strategies, no specific therapy yet exists for treatment of these potentially fatal illnesses. The oedema-reducing capacity of the lectin-like domain of TNF (TIP) and of synthetic peptides, mTIP and hTIP, which mimic the TIP domain of mouse and human TNF, have been demonstrated in various studies in rodents. Cell-based electrophysiological studies have revealed that the alveolar fluid clearing capacity of TNF and the TIP peptides is due to activation of the amiloride-sensitive Na(+) current in alveolar epithelial cells and that the primary site of action is on the apical side of these cells. AP301, a synthetic cyclic peptide mimicking the TIP domain of human TNF is currently undergoing clinical trials as a therapy for pulmonary permeability oedema. AP301 has been shown to improve alveolar liquid clearance and lung function in a porcine model of ALI. For non-clinical regulatory assessment, dog, pig and rat are standard animal models; accordingly, pre-clinical toxicological and pharmacological safety studies have been conducted with AP301 in dogs and rats. Hitherto, no studies have assessed the pharmacodynamic effect of AP301 on primary canine or porcine type II AEC. The current study describes the effect of AP301 on the amiloride-sensitive Na(+) current in type II AEC isolated from dog, pig and rat lungs. In whole cell patch clamp experiments with dog type II AEC, an increase in the amiloride-sensitive Na(+) current from 3.7 pA to 49.4 pA was observed in the presence of AP301; in pig type II AEC, an increase from 10.0 pA to 159.6 pA was observed, and in rat AEC, from 6.9 pA to 62.4 pA. In whole cell patch clamp experiments in A549 cells, AP301-induced enhancement of the amiloride-sensitive current was eliminated when Na(+) in the bath solution was replaced with N-methyl-d-glucamine (NMDG), and when the cells were pre-incubated with 5-aminoimidazole-4-carboxamide-1-ß-d-ribofuranoside (AICAR), an inhibitor of ENaC, but enhancement was unaffected by addition of cyclic nucleotide-gated (CNG) channel inhibitors Zn(2+) or l-cis-diltiazem prior to AP301. These results provide strong evidence that AP301 activates the amiloride-sensitive Na(+) current through ENaC in type II AEC from dog, pig and rat. To our knowledge, this is the first cell-based analysis of the oedema-clearing effect of AP301 observed in the porcine model of pulmonary oedema. Furthermore, the results validate the dog and pig models in non-clinical assessment of AP301.
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| 23313638 |
Total synthesis of bicyclic depsipeptides spiruchostatins C and D and investigation of their histone deacetylase inhibitory and antiproliferative activities |
10.1016/j.ejmech.2012.12.023. |
Eur J Med Chem |
Total synthesis of bicyclic depsipeptides spiruchostatins C and D and investigation of their histone deacetylase inhibitory and antiproliferative activities
Abstract
- The bicyclic depsipeptide histone deacetylase (HDAC) inhibitors spiruchostatins C and D were synthesized for the first time in a highly convergent and unified manner. The method features the amide coupling of a D-leucine-D-cysteine- or D-valine-D-cysteine-containing segment with a D-alanine- or D-valine-containing segment to directly assemble the corresponding seco-acids, key precursors of macrolactonization. The HDAC inhibitory assay and cell-growth inhibition analysis of the synthesized depsipeptides determined the order of potency of spiruchostatins A-D in comparison with the clinically approved depsipeptide FK228 (romidepsin). Novel aspects of structure-activity relationships (SAR) were revealed.
|
| 23342379 |
Isolation, structure elucidation and total synthesis of lajollamide A from the marine fungus Asteromyces cruciatus |
10.3390/md10122912. |
Mar Drugs |
Isolation, structure elucidation and total synthesis of lajollamide A from the marine fungus Asteromyces cruciatus
Abstract
- The marine-derived filamentous fungus Asteromyces cruciatus 763, obtained off the coast of La Jolla, San Diego, USA, yielded the new pentapeptide lajollamide A (1), along with the known compounds regiolone (2), hyalodendrin (3), gliovictin (4), ¹N-norgliovicitin (5), and bis-N-norgliovictin (6). The planar structure of lajollamide A (1) was determined by Nuclear Magnetic Resonance (NMR) spectroscopy in combination with mass spectrometry. The absolute configuration of lajollamide A (1) was unambiguously solved by total synthesis which provided three additional diastereomers of 1 and also revealed that an unexpected acid-mediated partial racemization (2:1) of the L-leucine and L-N-Me-leucine residues occurred during the chemical degradation process. The biological activities of the isolated metabolites, in particular their antimicrobial properties, were investigated in a series of assay systems.
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| 23354298 |
CYP3A5 gene variation influences cyclosporine A metabolite formation and renal cyclosporine disposition |
10.1097/TP.0b013e31827e6ad9. |
Transplantation |
CYP3A5 gene variation influences cyclosporine A metabolite formation and renal cyclosporine disposition
Abstract
- Higher concentrations of AM19 and AM1c9, secondary metabolites of cyclosporine A (CsA), have been associated with nephrotoxicity in organ transplant patients. The risk of renal toxicity may depend on the accumulation of CsA and its metabolites in the renal tissue. We evaluated the hypothesis that CYP3A5 genotype, and inferred enzyme expression, affects systemic CsA metabolite exposure and intrarenal CsA accumulation.
An oral dose of CsA was administered to 24 healthy volunteers who were selected based on their CYP3A5 genotype. CsA and its six main metabolites in whole blood and urine were measured by liquid chromatography-mass spectometry. In vitro incubations of CsA, AM1, AM9, and AM1c with recombinant CYP3A4 and CYP3A5 were performed to evaluate the formation pathways of AM19 and AM1c9.
The mean CsA oral clearance was similar between CYP3A5 expressors and xpressors. However, compared with CYP3A5 xpressors, the average blood area under the concentration-time curve (AUC) for AM19 and AM1c9 was 47.4% and 51.3% higher in CYP3A5 expressors (P=0.040 and 0.011, respectively), corresponding to 30% higher AUCmetabolite/AUCCsA ratios for AM19 and AM1c9 in CYP3A5 expressors. The mean apparent urinary CsA clearance based on a 48-hr collection was 20.4% lower in CYP3A5 expressors compared with CYP3A5 xpressors (4.2±1.0 and 5.3±1.3 mL/min, respectively; P=0.037), which is suggestive of CYP3A5-dependent intrarenal CsA metabolism.
At steady state, intrarenal accumulation of CsA and its secondary metabolites should depend on the CYP3A5 genotype of the liver and kidneys. This may contribute to interpatient variability in the risk of CsA-induced nephrotoxicity.
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| 23396208 |
Phosphorylation of FOXP3 controls regulatory T cell function and is inhibited by TNF-α in rheumatoid arthritis |
10.1038/nm.3085. |
Nat Med |
Phosphorylation of FOXP3 controls regulatory T cell function and is inhibited by TNF-α in rheumatoid arthritis
Abstract
- Regulatory T (Treg) cells suppress autoimmune disease, and impaired Treg cell function is associated with rheumatoid arthritis. Here we demonstrate that forkhead box P3 (FOXP3) transcriptional activity and, consequently, Treg cell suppressive function are regulated by phosphorylation at Ser418 in the C-terminal DNA-binding domain. In rheumatoid arthritis-derived Treg cells, the Ser418 site was specifically dephosphorylated by protein phosphatase 1 (PP1), whose expression and enzymatic activity were induced in the inflamed synovium by tumor necrosis factor α (TNF-α), leading to impaired Treg cell function. Moreover, TNF-α-induced Treg cell dysfunction correlated with increased numbers of interleukin-17 (IL-17)(+) and interferon-γ (IFN-γ)(+)CD4(+) T cells within the inflamed synovium in rheumatoid arthritis. Treatment with a TNF-α-specific antibody restored Treg cell function in subjects with rheumatoid arthritis, which was associated with decreased PP1 expression and increased FOXP3 phosphorylation in Treg cells. Thus, TNF-α controls the balance between Treg cells and pathogenic TH17 and TH1 cells in the synovium of individuals with rheumatoid arthritis through FOXP3 dephosphorylation.
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| 23411682 |
Synergistic effect of a novel cyclic pentadepsipeptide, neoN-methylsansalvamide, and paclitaxel on human multidrug resistance cancer cell lines |
10.1097/CAD.0b013e32835f060d. |
Anticancer Drugs |
Synergistic effect of a novel cyclic pentadepsipeptide, neoN-methylsansalvamide, and paclitaxel on human multidrug resistance cancer cell lines
Abstract
- NeoN-methylsansalvamide is a novel low-molecular-weight cyclic pentadepsipeptide that exerts cytotoxic effects on various human cancer cell lines. Its structural analysis using liquid chromatography mass/mass spectrometry showed the cyclic structure sequence -phenylalanine-leucine-valine-N-methylleucine-leucic acid-. The intrinsic cytotoxic and multidrug resistance reversal effects of neoN-methylsansalvamide were evaluated on the human cancer cell lines MES-SA and HCT15 as well as on their multidrug resistance sublines (MES-SA/DX5 and HCT15/CL05, respectively) using the sulforhodamine B assay. The EC50 values of paclitaxel for MES-SA, HCT15, and for the multidrug resistance sublines MES-SA/DX5 and HCT15/CL05 were 1.00±0.20, 0.85±0.63, 10.00±0.53, and >1000 nmol/l, respectively. However, the EC50 values for paclitaxel including 3 μmol/l neoN-methylsansalvamide for MES-SA/DX5, HCT15, and HCT15/CL02 were 1.58±0.12, 0.10±0.02, and 288.40±21.02 nmol/l, respectively. The in-vitro multidrug resistance reversal activity of neoN-methylsansalvamide was similar to that of the control verapamil. These finding suggests that a novel cyclic pentadepsipeptide, neoN-methylsansalvamide, is effective in reversing multidrug resistance in vitro, and this activity may be a major applicable biological function of this compound.
|
| 23418353 |
The E3 ubiquitin ligases RNF126 and Rabring7 regulate endosomal sorting of the epidermal growth factor receptor |
10.1242/jcs.116129. |
J Cell Sci |
The E3 ubiquitin ligases RNF126 and Rabring7 regulate endosomal sorting of the epidermal growth factor receptor
Abstract
- Activation of the epidermal growth factor receptor (EGFR) results in internalization and ubiquitin-dependent endosomal sorting, leading to lysosomal degradation. Here we describe the role of the RING-finger-domain-containing protein RNF126 and the related protein, Rabring7 in EGFR endosomal sorting. We demonstrate that RNF126 specifies K48-linked chains with UbcH5b and also functions with Ubc13/Uev1a to form K63-linked chains in vitro. RNF126 and Rabring7 associate with the EGFR through a ubiquitin-binding zinc finger domain and both E3 ubiquitin ligases promote ubiquitylation of EGFR. In the absence of c-Cbl or in cells expressing Cbl-70Z, the binding of RNF126 and Rabring7 to the EGFR is reduced, suggesting that RNF126 and Rabring7 function downstream of c-Cbl. In HeLa cells depleted of either RNF126 or Rabring7 the EGFR is retained in a late endocytic compartment and is inefficiently degraded. In addition, depletion of RNF126 or Rabring7 destabilizes ESCRT-II and reduces the number of multivesicular bodies formed after EGF stimulation. We also show that the depletion of Rabring7 attenuates the degradation of MET and that both RNF126 and Rabring7 regulate the sorting of CXCR4 from an early endocytic compartment. Together these data suggest that RNF126 and Rabring7 play a role in the ubiquitin-dependent sorting and downregulation of membrane receptors.
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