1.
Fluorinated and iodinated (Z)-2-(4-(2-fluoroethoxy)benzylidene)-5-iodobenzofuran-3(2H)-one.
Authors
Source
Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2011.
2011 Nov 30 [updated 2011 Dec 28].
Excerpt
Fluorinated and iodinated (Z)-2-(4-(2-fluoroethoxy)benzylidene)-5-iodobenzofuran-3(2H)-one (compound 3), abbreviated as [18F]3 and [125I]3, respectively, is an aurone derivative synthesized by Watanabe et al. for single-photon emission computed tomography (SPECT) and positron emission tomography (PET) of Alzheimer’s disease (AD) by targeting β-amyloid (Aβ) plaques (1). AD is characterized in pathology by the presence of extracellular Aβ plaques, intraneuronal neurofibrillary tangles, and neuronal loss in the cerebral cortex (2, 3). Of them, Aβ deposit is the earliest neuropathological marker and is relatively specific to AD and closely related disorders. Aβ plaques are composed of abnormal paired helical filaments 5–10 nm in size. These filaments are largely made of insoluble Aβ peptides that are 40 or 42 amino acids in length (4). In recent years, molecular imaging by targeting the extracellular Aβ has been intensively investigated in attempts to detect early AD, assess Aβ content in vivo, determine the timing of anti-plaque therapy, and evaluate the therapeutic efficacy (4). Radiolabeled Aβ40 peptides were tested first, but they showed poor penetration ability to cross the blood–brain barrier (BBB) (4). Based on the fact that Aβ can be specifically stained in vitro with dyes of Congo red, chrysamine G, and thioflavin-T, an effort was made to develop imaging agents with these dyes. This effort, however, was in general unsuccessful because the bulky ionic groups of heteroatoms in these dyes prevent them from crossing the BBB (2). Importantly, a large class of derivatives (e.g., aminonaphthalenes, benzothiazoles, stilbenes, and imidazopyridines) was synthesized with these dyes as templates (4). Clinical and preclinical studies have shown that these derivatives not only possess a high binding affinity with Aβ plaques as their parent compounds, but also exhibit good penetration ability through the BBB and rapid washout from brain. Ono et al. first synthesized a class of radioiodinated flavone derivatives that present a high binding affinity with Aβ plaques and good penetration ability through the BBB (5). However, these flavone derivatives display poor clearance from the brain, which leads to a high brain background. The investigators then explored another class of flavonoids with aurone as the core structure (6, 7). Aurone is a heterocyclic chemical compound that contains a benzofuran element associated with a benzylidene linked in position 2 and a chalcone-like group being closed into a five-member ring. The aurone derivatives possess a nucleophilic group (NH2, NHMe, or NMe2) at the 4' position and a radioiodine at the 5 position. Although these aurone derivatives exhibit a strong binding affinity with Aβ (inhibition constant (K i) = 1.2–6.8 nM), high penetration ability through the BBB (1.9%−4.6% injected dose per gram tissue (ID/g) at 2 min), and a fast washout from the brain (0.3%−0.5% ID/g at 30 min), the pharmacokinetics of these compounds are less favorable for brain imaging than the pharmacokinetics of the agent [123I]IMPY (6-iodo-2-(4'-dimethylamino)phenyl-imidazo[1,2]pyridine), which is the only SPECT agent to be tested in humans to date (1, 8, 9). The investigators also modified the flavone and aurone derivatives by pegylating them with 1–3 units of ethylene glycol at the 4' position or by conjugating them with the chelating agent bis-amino-bis-thiol (BAT) (7). Favorable pharmacokinetics for brain imaging was observed for the pegylated derivatives ([18F]8(a–c)) but not for the BAT-chelated derivatives ([99mTc]BAT-FL and [99mTc]BAT-AR) (6, 7). This series of chapters summarizes the data obtained with flavone and aurone derivatives, including [125I]15, [125I]9, [125I]14, [125I]16, [125I]17, [99mTc]BAT-FL, [99mTc]BAT-AR, [18F]8(a-c), [125I]3, and [18F]3 (1, 6-8). This chapter presents the data obtained with [125I]3 and [18F]3 (1).
Sections
Radioiodinated (Z)-2-(4-(2-hydroxyethoxy)benzylidene)-5-iodobenzofuran-3(2H)-one.
Authors
Source
Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2011.
2011 Nov 30 [updated 2011 Dec 28].
Excerpt
Radioiodinated (Z)-2-(4-(2-hydroxyethoxy)benzylidene)-5-iodobenzofuran-3(2H)-one (compound 15), abbreviated as [125I]15, is an aurone derivative synthesized by Maya et al. for single-photon emission computed tomography(SPECT) of Alzheimer’s disease (AD) by targeting β-amyloid (Aβ) (1). The other four aurone derivatives include radioiodinated (Z)-2-(4-methoxybenzylidene)-5-iodobenzofuran-3(2H)-one (compound 9), (Z)-2-(4-hydroxybenzylidene)-5-iodobenzofuran-3(2H)-one (compound 14), (Z)-2-(4-(2-(2-hydroxyethoxy)ethoxy)benzylidene)-5-iodobenzofuran-3(2H)-one (compound 16), and (Z)-2-(4-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)benzylidene)-5-iodobenzofuran-3(2H)-one (compound 17), which are abbreviated as [125I]9, [125I]14, [125I]16, and [125I]17, respectively. AD is characterized in pathology by the presence of extracellular Aβ plaques, intraneuronal neurofibrillary tangles, and neuronal loss in the cerebral cortex (2, 3). Of them, Aβ deposit is the earliest neuropathological marker and is relatively specific to AD and closely related disorders. Aβ plaques are composed of abnormal paired helical filaments 5–10 nm in size. These filaments are largely made of insoluble Aβ peptides that are 40 or 42 amino acids in length (4). In recent years, molecular imaging by targeting the extracellular Aβ has been intensively investigated in attempts to detect early AD, assess Aβ content in vivo, determine the timing of anti-plaque therapy, and evaluate the therapeutic efficacy (4). Radiolabeled Aβ40 peptides were tested first, but they showed poor penetration ability to cross the blood–brain barrier (BBB) (4). Based on the fact that Aβ can be specifically stained in vitro with dyes of Congo red, chrysamine G, and thioflavin-T, an effort was made to develop imaging agents with these dyes. This effort, however, was in general unsuccessful because the bulky ionic groups of heteroatoms in these dyes prevent them from crossing the BBB (2). Importantly, a large class of derivatives (e.g., aminonaphthalenes, benzothiazoles, stilbenes, and imidazopyridines) was synthesized with these dyes as templates (4). Clinical and preclinical studies have shown that these derivatives not only possess a high binding affinity with Aβ plaques as their parent compounds, but also exhibit good penetration ability through the BBB and rapid washout from brain with low to no plaque deposits. Ono et al. first synthesized a class of radioiodinated flavone derivatives that present a high binding affinity with Aβ plaques and good penetration ability through the BBB (5). However, these flavone derivatives display poor clearance from the brain, which leads to a high brain background. The investigators then explored another class of flavonoids with aurone as the core structure (6, 7). Aurone is a heterocyclic chemical compound that contains a benzofuran element associated with a benzylidene linked in position 2 and a chalcone-like group being closed into a five-member ring. The aurone derivatives possess a nucleophilic group (NH2, NHMe, or NMe2) at the 4' position and a radioiodine at the 5 position. Although these aurone derivatives exhibit a strong binding affinity with Aβ (inhibition constant (K i) = 1.2–6.8 nM), high penetration ability through the BBB (1.9%−4.6% injected dose per gram tissue (ID/g) at 2 min), and a fast washout from the brain (0.3%−0.5% ID/g at 30 min), the pharmacokinetics of these compounds are less favorable for brain imaging than the pharmacokinetics of the agent [123I]IMPY (6-iodo-2-(4'-dimethylamino)phenyl-imidazo[1,2]pyridine), which is the only SPECT agent to be tested in humans to date (1, 8, 9). The investigators also modified the flavone and aurone derivatives by pegylating them with 1–3 units of ethylene glycol at the 4' position or by conjugating them with the chelating agent bis-amino-bis-thiol (BAT) (7). Favorable pharmacokinetics for brain imaging was observed for the pegylated derivatives ([18F]8(a–c)) but not for the BAT-chelated derivatives ([99mTc]BAT-FL and [99mTc]BAT-AR) (6, 7). This series of chapters summarizes the data obtained with flavone and aurone derivatives, including [125I]15, [125I]9, [125I]14, [125I]16, [125I]17, [99mTc]BAT-FL, [99mTc]BAT-AR, [18F]8(a–c), [125I]3, and [18F]3 (1, 6-8). This chapter presents the data obtained with [125I]15, [125I]9, [125I]14, [125I]16, and [125I]17 (1).
Sections
99mTc-Bis-amino-bis-thiol-conjugated 6-(3-bromopropoxy)-2-(4-(dimethylamino)phenyl)-4H-chromen-4-one and (Z)-5-(3-bromopropoxy)-2-(4-(dimethylamino)benzylidene)benzofuran-3(2H)-one.
Authors
Source
Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2011.
2011 Nov 30 [updated 2011 Dec 28].
Excerpt
99mTc-Bis-amino-bis-thiol (BAT)-conjugated 6-(3-bromopropoxy)-2-(4-(dimethylamino)phenyl)-4H-chromen-4-one and (Z)-5-(3-bromopropoxy)-2-(4-(dimethylamino)benzylidene)benzofuran-3(2H)-one, abbreviated as [99mTc]BAT-FL and [99mTc]BAT-AR, respectively, are flavone and aurone derivatives synthesized by Ono et al. for single-photon emission computed tomography (SPECT) of Alzheimer’s disease (AD) by targeting β-amyloid (Aβ) (1). AD is characterized in pathology by the presence of extracellular Aβ plaques, intraneuronal neurofibrillary tangles, and neuronal loss in the cerebral cortex (2, 3). Of them, Aβ deposit is the earliest neuropathological marker and is relatively specific to AD and closely related disorders. Aβ plaques are composed of abnormal paired helical filaments 5–10 nm in size. These filaments are largely made of insoluble Aβ peptides that are 40 or 42 amino acids in length (4). In recent years, molecular imaging by targeting the extracellular Aβ has been intensively investigated in attempts to detect early AD, assess Aβ content in vivo, determine the timing of anti-plaque therapy, and evaluate the therapeutic efficacy (4). Radiolabeled Aβ40 peptides were tested first, but they showed poor penetration ability to cross the blood–brain barrier (BBB) (4). Based on the fact that Aβ can be specifically stained in vitro with dyes of Congo red, chrysamine G, and thioflavin-T, an effort was made to develop imaging agents with these dyes. This effort, however, was in general unsuccessful because the bulky ionic groups of heteroatoms in these dyes prevent them from crossing the BBB (2). Importantly, a large class of derivatives (e.g., aminonaphthalenes, benzothiazoles, stilbenes, and imidazopyridines) was synthesized with these dyes as templates (4). Clinical and preclinical studies have shown that these derivatives not only possess a high binding affinity with Aβ plaques as their parent compounds, but also exhibit good penetration ability through the BBB and rapid washout from brain with low to no plaque deposits. Ono et al. first synthesized a class of radioiodinated flavone derivatives that present a high binding affinity with Aβ plaques and good penetration ability through the BBB (5). However, these flavone derivatives display poor clearance from the brain, which leads to a high brain background. The investigators then explored another class of flavonoids with aurone as the core structure (1, 6). Aurone is a heterocyclic chemical compound that contains a benzofuran element associated with a benzylidene linked in position 2 and a chalcone-like group closed into a five-member ring. The aurone derivatives possess a nucleophilic group (NH2, NHMe, or NMe2) at the 4' position and a radioiodine at the 5 position. Although these aurone derivatives exhibit a strong binding affinity with Aβ (inhibition constant (K i) = 1.2–6.8 nM), high penetration ability through the BBB (1.9%−4.6% injected dose per gram tissue (ID/g) at 2 min), and a fast washout from the brain (0.3%−0.5% ID/g at 30 min), the pharmacokinetics of these compounds are less favorable for brain imaging than the pharmacokinetics of the agent [123I]IMPY (6-iodo-2-(4'-dimethylamino)phenyl-imidazo[1,2]pyridine), which is the only SPECT agent to be tested in humans to date (7-9). The investigators also modified the flavone and aurone derivatives by pegylating them with 1–3 units of ethylene glycol at the 4' position or by conjugating them with the chelating agent bis-amino-bis-thiol (BAT). Favorable pharmacokinetics for brain imaging was observed for the pegylated derivatives ([18F]8(a–c)) but not for the BAT-chelated derivatives ([99mTc]BAT-FL and [99mTc]BAT-AR) (1, 6). This series of chapters summarizes the data obtained with flavone and aurone derivatives, including [125I]15, [125I]9, [125I]14, [125I]16, [125I]17, [99mTc]BAT-FL, [99mTc]BAT-AR, [18F]8(a–c), [125I]3, and [18F]3 (1, 6-8). This chapter presents the data obtained with [99mTc]BAT-FL and [99mTc]BAT-AR (1).
Sections
18F-Labeled fluoropegylated 6-fluoroethoxy-4'-dimethylaminoflavone, 6-(2-(2-fluoro-ethoxy)-ethoxy)-4'-dimethylaminoflavone, and 6-(2-(2-(2-fluoro-ethoxy)-ethoxy)ethoxy)-4'-dimethylaminoflavone.
Authors
Source
Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004-2011.
2011 Nov 30 [updated 2011 Dec 28].
Excerpt
18F-Labeled fluoropegylated 6-fluoroethoxy-4'-dimethylaminoflavone (compound 8a), 6-(2-(2-fluoro-ethoxy)-ethoxy)-4'-dimethylaminoflavone (compound 8b), and 6-(2-(2-(2-fluoro-ethoxy)-ethoxy)ethoxy)-4'-dimethylaminoflavone (compound 8c), abbreviated as [18F]8a, [18F]8b, and [18F]8c, respectively, are flavone derivatives synthesized by Ono et al. for positron emission tomography (PET) of Alzheimer’s disease (AD) by targeting β-amyloid (Aβ) (1). AD is characterized in pathology by the presence of extracellular Aβ plaques, intraneuronal neurofibrillary tangles, and neuronal loss in the cerebral cortex (2, 3). Of them, Aβ deposit is the earliest neuropathological marker and is relatively specific to AD and closely related disorders. Aβ plaques are composed of abnormal paired helical filaments 5–10 nm in size. These filaments are largely made of insoluble Aβ peptides that are 40 or 42 amino acids in length (4). In recent years, molecular imaging by targeting the extracellular Aβ has been intensively investigated in attempts to detect early AD, assess Aβ content in vivo, determine the timing of anti-plaque therapy, and evaluate the therapeutic efficacy (4). Radiolabeled Aβ40 peptides were tested first, but they showed poor penetration ability to cross the blood–brain barrier (BBB) (4). Based on the fact that Aβ can be specifically stained in vitro with dyes of Congo red, chrysamine G, and thioflavin-T, an effort was made to develop imaging agents with these dyes. This effort, however, was in general unsuccessful because the bulky ionic groups of heteroatoms in these dyes prevent them from crossing the BBB (2). Importantly, a large class of derivatives (e.g., aminonaphthalenes, benzothiazoles, stilbenes, and imidazopyridines) was synthesized with these dyes as templates (4). Clinical and preclinical studies have shown that these derivatives not only possess a high binding affinity with Aβ plaques as their parent compounds, but also exhibit good penetration ability through the BBB and rapid washout from brain with low to no plaque deposits. Ono et al. first synthesized a class of radioiodinated flavone derivatives that present a high binding affinity with Aβ plaques and good penetration ability through the BBB (5). However, these flavone derivatives display poor clearance from the brain, which leads to a high brain background. The investigators then explored another class of flavonoids with aurone as the core structure (1, 6). Aurone is a heterocyclic chemical compound that contains a benzofuran element associated with a benzylidene linked in position 2 and a chalcone-like group being closed into a five-member ring. The aurone derivatives possess a nucleophilic group (NH2, NHMe, or NMe2) at the 4' position and a radioiodine at the 5 position. Although these aurone derivatives exhibit a strong binding affinity with Aβ (inhibition constant (K i) = 1.2–6.8 nM), high penetration ability through the BBB (1.9%−4.6% injected dose per gram tissue (ID/g) at 2 min), and a fast washout from the brain (0.3%−0.5% ID/g at 30 min), the pharmacokinetics of these compounds are less favorable for brain imaging than the pharmacokinetics of the agent [123I]IMPY (6-iodo-2-(4'-dimethylamino)phenyl-imidazo[1,2]pyridine), which is the only SPECT agent to be tested in humans to date (7-9). The investigators also modified the flavone and aurone derivatives by pegylating them with 1–3 units of ethylene glycol at the 4' position or by conjugating them with the chelating agent bis-amino-bis-thiol (BAT). Favorable pharmacokinetics for brain imaging was observed for the pegylated derivatives ([18F]8(a–c)) but not for the BAT-chelated derivatives ([99mTc]BAT-FL and [99mTc]BAT-AR) (1, 6). This series of chapters summarizes the data obtained with flavone and aurone derivatives, including [125I]15, [125I]9, [125I]14, [125I]16, [125I]17, [99mTc]BAT-FL, [99mTc]BAT-AR, [18F]8(a–c), [125I]3, and [18F]3 (1, 6-8). This chapter presents the data obtained with [18F]8(a–c) (1).
Sections
Understanding the α-crystallin cell membrane conjunction.
Abstract
PURPOSE:
It is well established that levels of soluble α-crystallin in the lens cytoplasm fall steadily with age, accompanied by a corresponding increase in the amount of membrane-bound α-crystallin. Less well understood, is the mechanism driving this age-dependent membrane association. The aim of this study was to investigate the role of the membrane and its associated proteins and peptides in the binding of α-crystallin.
METHODS:
Fiber cell membranes from human and bovine lenses were separated from soluble proteins by centrifugation. Membranes were stripped of associated proteins with successive aqueous, urea, and alkaline solutions. Protein constituents of the respective membrane isolates were examined by SDS-PAGE and western immunoblotting. Recombinant αA- and αB-crystallins were fluorescently-labeled with Alexa350(®) dye and incubated with the membrane isolates and the binding capacity of membrane for α-crystallin was determined.
RESULTS:
The binding capacity of human membranes was consistently higher than that of bovine membranes. Urea- and alkali-treated membranes from the nucleus had similar binding capacities for αA-crystallin, which were significantly higher than both cortical membrane extracts. αB-Crystallin also had a higher affinity for nuclear membrane. However, urea-treated nuclear membrane had three times the binding capacity for αB-crystallin as compared to the alkali-treated nuclear membrane. Modulation of the membrane-crystallin interaction was achieved by the inclusion of an NH(2)-terminal peptide of αB-crystallin in the assays, which significantly increased the binding. Remarkably, following extraction with alkali, full length αA- and αB-crystallins were found to remain associated with both bovine and human lens membranes.
CONCLUSIONS:
Fiber cell membrane isolated from the lens has an inherent capacity to bind α-crystallin. For αB-crystallin, this binding was found to be proportional to the level of extrinsic membrane proteins in cells isolated from the lens nucleus, indicating these proteins may play a role in the recruitment of αB-crystallin. No such relationship was evident for αA-crystallin in the nucleus, or for cortical membrane binding. Intrinsic lens peptides, which increase in abundance with age, may also function to modulate the interaction between soluble α-crystallin and the membrane. In addition, the tight association between α-crystallin and the lens membrane suggests that the protein may be an intrinsic component of the membrane structure.
- PMID:
- 22219626
- [PubMed - in process]
CD26/DPP-4 inhibition recruits regenerative stem cells via stromal cell-derived factor-1 and beneficially influences ischaemia-reperfusion injury in mouse lung transplantation.
Source
Division of Thoracic Surgery, University Hospital Zurich, Zurich, Switzerland.
Abstract
OBJECTIVESThe CD26 antigen is a transmembrane glycoprotein that is constitutively expressed on activated lymphocytes and in pulmonary parenchyma. This molecule is also identified as dipeptidyl peptidase-4 (DPP-4) that cleaves a host of biologically active peptides. Here, we aimed to identify an important substrate of CD26/DPP-4-stromal cell-derived factor-1 (SDF-1/CXCL12)-as a key modulator for stem-cell homing together with its receptor CXCR4 in response to ischaemic injury of the lung.METHODSOrthotopic single lung transplantation (Tx) was performed between syngeneic C57BL/6 mice. Inhibition of CD26/DPP-4 activity in recipients was achieved using vildagliptin (10 mg/kg, every 12 h) subcutaneously, and 6 h ischaemia time was applied prior to implantation. Forty-eight hours after Tx, lung histology, SDF-1 levels (enzyme-linked immunosorbent assay) in lung, spleen and plasma, and expression of the SDF-1 receptor CXCR4 in blood and lung were assessed. Homing of regenerative progenitor cells to the transplanted lung was evaluated using fluorescent-activated cell sorting.RESULTSCompared with untreated lung transplanted mice, systemic DPP-4 inhibition of Tx recipients resulted in an increase in protein concentration of SDF-1 in plasma, spleen and lung. Concordantly, the frequency of cells bearing the SDF-1 receptor CXCR4 rose significantly in the circulation and also in the lungs of DPP-4-inhibited recipients. We found co-expression of CXCR4/CD34 in the grafts of animals treated with vildagliptin, and the stem-cell markers Flt-3 and c-kit were present on a significantly increased number of cells. The morphology of grafts from DPP-4 inhibitor-treated recipients revealed less alveolar oedema when compared with untreated recipients.CONCLUSIONSTargeting the SDF-1-CXCR4 axis through CD26/DPP-4 inhibition increased the intragraft number of progenitor cells contributing to the recovery from ischaemia-reperfusion lung injury. Stabilization of endogenous SDF-1 is achievable and may be a promising strategy to intensify sequestration of regenerative stem cells and thus emerges as a novel therapeutic concept.
- PMID:
- 22219460
- [PubMed - as supplied by publisher]
Transgenic Mouse Model Expressing the Caspase 6 Fragment of Mutant Huntingtin.
Source
Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Departments of Neurology, Pharmacology, and Neuroscience, and Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, and Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702.
Abstract
Huntington's disease (HD) is caused by a polyglutamine expansion in the Huntingtin (Htt) protein. Proteolytic cleavage of Htt into toxic N-terminal fragments is believed to be a key aspect of pathogenesis. The best characterized putative cleavage event is at amino acid 586, hypothesized to be mediated by caspase 6. A corollary of the caspase 6 cleavage hypothesis is that the caspase 6 fragment should be a toxic fragment. To test this hypothesis, and further characterize the role of this fragment, we have generated transgenic mice expressing the N-terminal 586 aa of Htt with a polyglutamine repeat length of 82 (N586-82Q), under the control of the prion promoter. N586-82Q mice show a clear progressive rotarod deficit by 4 months of age, and are hyperactive starting at 5 months, later changing to hypoactivity before early mortality. MRI studies reveal widespread brain atrophy, and histologic studies demonstrate an abundance of Htt aggregates, mostly cytoplasmic, which are predominantly composed of the N586-82Q polypeptide. Smaller soluble N-terminal fragments appear to accumulate over time, peaking at 4 months, and are predominantly found in the nuclear fraction. This model appears to have a phenotype more severe than current full-length Htt models, but less severe than HD mouse models expressing shorter Htt fragments. These studies suggest that the caspase 6 fragment may be a transient intermediate, that fragment size is a factor contributing to the rate of disease progression, and that short soluble nuclear fragments may be most relevant to pathogenesis.
- PMID:
- 22219281
- [PubMed - as supplied by publisher]
Kinetic mechanism of protein arginine methyltransferase 6.
Source
Emory University, United States;
Abstract
The Protein Arginine Methyltransferases (PRMTs) are a family of enzymes that catalyze the mono- and dimethylation of arginine residues in a variety of proteins. Although these enzymes play important roles in a variety of cellular processes, aberrant PRMT activity is associated with several disease states, including heart disease and cancer. In an effort to guide the development of inhibitors targeting individual PRMTs, we initiated studies to characterize the molecular mechanisms of PRMT catalysis. Herein, we report studies on the kinetic mechanism of PRMT6. Initial velocity, product inhibition, and dead-end analogue inhibition studies with the AcH4-21 and R1 peptides, as well as their monomethylated versions, indicate, in contrast to a previous report, that PRMT6 utilizes a rapid equilibrium random mechanism with dead-end EAP and EBQ complexes.
- PMID:
- 22219200
- [PubMed - as supplied by publisher]
Tannic Acid is a Natural β-secretase Inhibitor that Prevents Cognitive Impairment and Mitigates Alzheimer-like Pathology in Transgenic Mice.
Source
Saitama Medical Center and University, Japan;
Abstract
Amyloid precursor protein (APP) proteolysis is essential for production of amyloid-β (Aβ) peptides that form β-amyloid plaques in brains of Alzheimer disease (AD) patients. Recent focus has been directed toward a group of naturally-occurring anti-amyloidogenic polyphenols known as flavonoids. We orally administered the flavonoid tannic acid (TA) to the transgenic PSAPP mouse model of cerebral amyloidosis (bearing mutant human APP and presenilin-1 transgenes) and evaluated cognitive function and AD-like pathology. Consumption of TA for 6 months prevented transgene-associated behavioral impairment including hyperactivity, decreased object recognition, and defective spatial reference memory, but did not alter non-transgenic mouse behavior. Accordingly, brain parenchymal and cerebral vascular β-amyloid deposits and abundance of various Aβ species including oligomers were mitigated in TA-treated PSAPP mice. These effects occurred with decreased cleavage of the β-carboxyl-terminal APP fragment, lowered soluble APP-β production, reduced β-site APP cleaving enzyme 1 protein stability and activity, and attenuated neuroinflammation. As in vitro validation, we treated well-characterized mutant human APP-overexpressing murine neuron-like cells with TA and found significantly reduced Aβ production associated with less amyloidogenic APP proteolysis. Taken together, these results raise the possibility that dietary supplementation with TA may be prophylactic for AD by inhibiting β-secretase activity and neuroinflammation and thereby mitigating AD pathology.
- PMID:
- 22219198
- [PubMed - as supplied by publisher]
C-terminal mutations destabilize Sil1/BAP can cause Marinesco-Sjogren Syndrome.
Source
The Institute of Cancer Research, United Kingdom;
Abstract
Marinesco-Sjogren syndrome (MSS) is an autosomal recessive, neurodegenerative, multi-system disorder characterized by severe phenotypes developing in infancy. Recently mutations in the endoplasmic reticulum (ER) associated co-chaperone Sil1/BAP were identified to be the major cause of MSS. Sil1 acts as a nucleotide exchange factor for BiP, the ER Hsp70 orthologue, which plays an essential role in the folding and assembly of nascent polypeptide chains in the ER. Nucleotide exchange facilitates the release of BiP from substrates enabling the subsequent folding and transport of the protein. Although most mutations leading to MSS result in deletion of the majority of the protein, three separate mutations have been identified that disrupt only the last five or six amino acids of the protein, which were assumed to encode a divergent ER retention motif. This study presents an in depth analysis of two of these mutants and reveals that the phenotype in the affected individuals is not likely due to depletion of Sil1 from the ER via secretion. Instead, our analyses show that the mutant proteins are particularly unstable and either form large aggregates in the ER or are rapidly degraded via the proteasome. In agreement with our findings, homology modeling suggests that the very C-terminal residues of Sil1 play a role in its structural integrity rather than its localization. These new insights might be a first step towards a possible pharmacological treatment of certain types of MSS by specifically stabilizing the mutant Sil1 protein.
- PMID:
- 22219183
- [PubMed - as supplied by publisher]
Comparison of receptor affinity of (nat)Sc-DOTA-TATE versus (nat)Ga-DOTA-TATE.
Abstract
BACKGROUND:
(44)Sc as a positron emitter can be an interesting alternative to (68)Ga (T(½) = 67.71 min) due to its longer half-life (T(½) = 3.97 h). Moreover, the b- emitter (47)Sc can be used for therapy when attached to the same biomolecule vectors. DOTA as a chelating agent has been proven suitable for the radiolabelling of peptides recognising tumour cell receptors in vivo with M(3+) radiometals. DOTA-derivatized peptides have been successfully labelled with (90)Y and (177)Lu for therapy, and with (68)Ga for PET imaging. However, published data on (44)Sc-labelled DOTA-biomolecules as potential PET radiotracers are still very limited. The aim of this study was to compare the affinity of (nat)Ga- and (nat)Sc-labelled DOTA-TATE to somatostatin receptors subtype 2 expressed in rat pancreatic cancer cell line AR42J.
MATERIAL AND METHODS:
The cold complexes of DOTA-TATE with (nat)Ga and (nat)Sc were synthesized and identified by HPLC and MS analysis and evaluated in vitro for competitive binding to cancer cell line AR42J expressing somatostatin receptors subtype 2 (sstr2).
RESULTS:
The IC50 values calculated from the displacement curve of {(125)I-Tyr(11)}-SST-14 were: 0.20 ± 0.18, 0.70 ± 0.20, 0.64 ± 0.22 and 0.67 ± 0.12 for (nat)Ga-DOTA-TATE, (nat)Sc-DOTA-TATE, DOTA-TATE, and {Tyr(11)}-SST-14 complexes, respectively, with the affinity lowering in the decreasing order: (nat)Ga-DOTA-TATE 〉 DOTA-TATE 〉 Tyr(11)-SST-14 〉 (nat)Sc-DOTA-TATE.
CONCLUSIONS:
The binding affinity of (nat)Ga-DOTA-TATE appeared higher than that of (nat)Sc-DOTA-TATE. Further in vitro and in vivo studies are needed to verify the influence of the chelated metal on the affinity and uptake of the respective radiolabelled compounds. This information might be crucial when the in vivo applications of peptides labelled with (68)Ga and (44)Sc for PET, as well as the use of 47Sc for radiotherapy are considered. Nuclear Med Rev 2011; 14, 2: 85-89.
- PMID:
- 22219148
- [PubMed - in process]
Disfavoring Macrocycle b Fragments by Constraining Torsional Freedom: The "Twisted" Case of QWFGLM b(6).
Source
Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL, 32611-7200, USA.
Abstract
While recent studies have shown that for some peptides, such as oligoglycines and Leu-enkephalin, mid-sized b fragment ions exist as a mixture of oxazolone and macrocycle structures, other primary structure motifs, such as QWFGLM, are shown to exclusively give rise to macrocycle structures. The aim of this study was to determine if certain amino acid residues are capable of suppressing macrocycle formation in the corresponding b fragment. The residues proline and 4-aminomethylbenzoic acid (4AMBz) were chosen because of their intrinsic rigidity, in the expectation that limited torsional flexibility may impede "head-to-tail" macrocycle formation. The presence of oxazolone versus macrocycle b(6) fragment structures was validated by infrared multiple photon dissociation (IRMPD) spectroscopy, using the free electron laser FELIX. It is confirmed that proline disfavors macrocycle formation in the cases of QPWFGLM b(7) and in QPFGLM b(6). The 4AMBz substitution experiments show that merely QWFG(4AMBz)M b(6), with 4AMBz in the fifth position, exhibits a weak oxazolone band. This effect is likely ascribed to a stabilization of the oxazolone structure, due to an extended oxazolone ring-phenyl π-electron system, not due to the rigidity of the 4AMBz residue. These results show that some primary structures have an intrinsic propensity to form macrocycle structures, which is difficult to disrupt, even using residues with limited torsional flexibility.
- PMID:
- 22219043
- [PubMed - as supplied by publisher]
The use of plants for the production of therapeutic human peptides.
Source
Laboratorio di Biotecnologie, Unità Tecnica BIORAD, ENEA C.R. Casaccia, 00123, Rome, Italy.
Abstract
Peptides have unique properties that make them useful drug candidates for diverse indications, including allergy, infectious disease and cancer. Some peptides are intrinsically bioactive, while others can be used to induce precise immune responses by defining a minimal immunogenic region. The limitations of peptides, such as metabolic instability, short half-life and low immunogenicity, can be addressed by strategies such as multimerization or fusion to carriers, to improve their pharmacological properties. The remaining major drawback is the cost of production using conventional chemical synthesis, which is also difficult to scale-up. Over the last 15 years, plants have been shown to produce bioactive and immunogenic peptides economically and with the potential for large-scale synthesis. The production ofpeptides in plants is usually achieved by the genetic fusion of the corresponding nucleotide sequence to that of a carrier protein, followed by stable nuclear or plastid transformation or transient expression using bacterial or viral vectors. Chimeric plant viruses or virus-like particles can also be used to display peptide antigens, allowing the production of polyvalent vaccine candidates. Here we review progress in the field of plant-derived peptides over the last 5 years, addressing new challenges for diverse pathologies.
- PMID:
- 22218674
- [PubMed - as supplied by publisher]
Solid state NMR studies of oligourea foldamers: Interaction of (15)N-labelled amphiphilic helices with oriented lipid membranes.
Source
Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Faculté de chimie, 4 rue Blaise Pascal, 67070 Strasbourg, France. bechinger@unistra.fr.
Abstract
Synthetic oligomers that are derived from natural polypeptide sequences, albeit with unnatural building blocks, have attracted considerable interest in mimicking bioactive peptides and proteins. Many of those compounds adopt stable folds in aqueous environments that resemble protein structural elements. Here we have chemically prepared aliphatic oligoureas and labeled them at selected positions with (15)N for structural investigations using solid-state NMR spectroscopy. In the first step, the main tensor elements and the molecular alignment of the (15)N chemical shift tensor were analyzed. This was possible by using a two-dimensional heteronuclear chemical shift/dipolar coupling correlation experiment on a model compound that represents the chemical, and thereby also the chemical shift characteristics, of the urea bond. In the next step (15)N labeled versions of an amphipathic oligourea, that exert potent antimicrobial activities and that adopt stable helical structures in aqueous environments, were prepared. These compounds were reconstituted into oriented phospholipid bilayers and the (15)N chemical shift and (1)H-(15)N dipolar couplings of two labeled sites were determined by solid-state NMR spectroscopy. The data are indicative of an alignment of this helix parallel to the membrane surface in excellent agreement with the amphipathic character of the foldamer and consistent with previous models explaining the antimicrobial activities of α-peptides.
- PMID:
- 22218372
- [PubMed - as supplied by publisher]
Pseudomorphic synthesis of monodisperse magnetic mesoporous silica microspheres for selective enrichment of endogenous peptides.
Source
Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China.
Abstract
In this work, we describe a novel synthetic strategy of magnetic mesoporous silica spheres (Fe(3)O(4)@mSiO(2)) for the selective enrichment of endogenous peptides. Fe(3)O(4) particles were coated with silica shell by a sol-gel method, followed by pseudomorphic synthesis to transform nonporous silica shell into ordered mesoporous silica shell. The core/shell structure and mesostructure were individually fabricated in two steps, which can be expedient to independently optimize the properties of monodispersion, magnetization and mesostructure. Actually, it was confirmed that the produced Fe(3)O(4)@mSiO(2) particles possess good monodispersion, high magnetization, superparamagnetism, uniform accessible mesopores, and large surface area and pore volume. With these good properties, Fe(3)O(4)@mSiO(2) spheres were applied to the rapid enrichment of peptides. Based on the size-exclusion mechanism and hydrophobic interaction with siloxane bridge group mainly on the surface of inside pores, Fe(3)O(4)@mSiO(2) can selectively capture peptides and exclude high-MW proteins and salts. Furthermore, peptides in human plasma were successfully enriched by Fe(3)O(4)@mSiO(2).
Copyright © 2011 Elsevier B.V. All rights reserved.
- PMID:
- 22218330
- [PubMed - as supplied by publisher]
The effect of lipid droplet size on satiety and peptide secretion is intestinal site-specific.
Source
Department of Internal Medicine, Division of Gastroenterology-Hepatology, University Hospital Maastricht, Maastricht, The Netherlands; Department of Gastroenterology, Leiden University Medical Centre, Leiden, The Netherlands.
Abstract
BACKGROUND & AIMS:
: Infusion of fat into the small intestine induces satiety. Reducing fat droplet size accelerates fat digestion, but the effect on satiety after ileal fat infusion is not known. The aim of the study was to compare the effects of fat emulsions differing in droplet size (fine, coarse) infused in either duodenum or ileum on satiety, gastric emptying and peptide secretion.
METHODS:
In a randomized single-blind crossover study 15 healthy volunteers received, after intubation with a nasoileal tube, 4 different treatments on 4 consecutive days. After consumption of a liquid meal, 6 g of fine or coarse fat emulsion was infused into duodenum or ileum. Study parameters were satiety, gastric emptying and gut peptides. These parameters were statistically evaluated using ANCOVA.
RESULTS:
In the duodenum, Fine emulsion significantly reduced hunger, increased fullness, delayed gastric emptying, but did not affect peptide secretion versus Coarse. In the ileum, Fine emulsion did not affect hunger, fullness, or gastric emptying, but significantly increased peptide secretion versus Coarse.
CONCLUSIONS:
Compared to larger fat droplets, smaller droplets significantly affect satiety, gastric emptying and gut peptide release, but with the effect being dependent on the intestinal location of fat delivery. DUTCH TRIALREGISTER: NTR1515.
Copyright © 2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
- PMID:
- 22217980
- [PubMed - as supplied by publisher]
Differential expression and processing of secretogranin II in relation to the status of pheochromocytoma : implications for the production of the tumoral marker EM66.
Source
J Guillemot, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, European Institute for Peptide Research (IFRMP 23), University of Rouen, Mont-Saint-Aignan, France.
Abstract
We have previously demonstrated that measurement of tissue concentrations of the secretogranin II (SgII)-derived peptide EM66, may help to discriminate between benign and malignant pheochromocytomas and that EM66 represents a sensitive plasma marker of pheochromocytomas. Here, we investigated the gene expression and protein production of SgII in 13 normal adrenal glands, and 35 benign and 16 malignant pheochromocytomas with the goal to examine the molecular mechanisms leading to the marked variations of expression of EM66 in tumoral chromaffin tissue. EM66 levels were 16-fold higher in benign than in malignant pheochromocytomas and had an area under the ROC curve of 0.95 for distinction of benign and malignant tumors. Q-PCR experiments indicated that the SgII gene was significantly underexpressed in malignant compared to benign tumors. Western blot analysis using antisera directed against SgII and SgII-derived fragments revealed lower SgII protein and SgII-processing products in malignant tumors. Western blot also showed that low p-CREB concentrations seemed to be associated with the malignant status. In addition, the prohormone convertase PC1 and PC2 genes and proteins were overexpressed in benign compared to malignant pheochromocytomas. Low concentrations of EM66 found in malignant tumors are associated with reduced expression and production of SgII and SgII-derived peptides that could be ascribed to a decrease in SgII gene transcription, probably linked to p-CREB down-regulation, and to lower PC levels. These findings highlight the mechanisms leading to lower concentrations of EM66 in malignant pheochromocytoma and strengthen the notion that this peptide is a suitable marker of this neuroendocrine tumor.
- PMID:
- 22217803
- [PubMed - as supplied by publisher]
Cooperative antitumor effect of endothelial-monocyte activating polypeptide II and flutamide on human prostate cancer xenografts.
Source
V.P. Komisarenko Institute of Endocrinology and Metabolism, Academy of MedicalSciences of Ukraine, Kyiv, Ukraine.
Abstract
Recombinant cytokine-like endothelial monocyte-activating polypeptide II (EMAP II) and antiandrogen flutamide target different mechanisms of growth of androgen-dependent prostate cancer (PC). The aim of this study was to clarify whether combined treatment with EMAP II and flutamide is more effective than monotherapy with regard to retardation of PC progression. Materials and Methods: Antitumor effects of EMAP II (10 µg/kg b.w./d, s.c., 3d), or flutamide (10 mg/kg b.w./d, per os, 3d), or their combination were studied in CBA male mice bearing human androgen-dependent PC xenografts for 7 days. Androgen-dependent phenotype of the tumors was verified in preliminary castrated mice. The xenografts were weighed and underwent a histopathologic examination. The results were compared with those of non-treated mice. Results: EMAP II and flutamide used separately inhibited growth of the xenografts by 74% and 53% respectively. Both drugs caused destructive changes in malignant epithelial cells along with leukocyte infiltration of the tumor. Combined treatment inhibited tumor growth by 85%, and was more effective than monotherapy with regard to morphological changes. Conclusions: This study demonstrates cooperative inhibitory effect of EMAP II and flutamide on growth and morphology of human PC xenografts that could represent a new modality of palliative treatment of this disease.
- PMID:
- 22217713
- [PubMed - in process]
Soy peptide-induced stem cell proliferation: involvement of ERK and TGF-β1.
Abstract
This study was conducted to investigate the proliferative effect of vegetable soy peptides on adult stem cells (ASCs) in the absence of serum and their possible mechanisms of action. The proliferation of human adipose tissue-derived mesenchymal stem cells (ADSCs) and cord blood-derived mesenchymal stem cells (CB-MSCs) treated with soypeptides was found to increase significantly upon 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Click-iT 5-ethynyl-2'-deoxyuridine flow cytometry assay. In addition, soy peptides led to stepwise phosphorylation of the p44/42 MAPK (ERK), mammalian target of rapamycin (mTOR), p70 S6 kinase, S6 ribosomal protein (S6RP) and eukaryotic initiation factor 4E (eIF4E) in ADSCs. Furthermore, quantitative analysis of the cytokines revealed that the production of transforming growth factor-beta1 (TGF-β1), vascular endothelial growth factor and interleukin-6 increased significantly in response to treatment with soy peptides in both ADSCs and CB-MSCs. Similarly, soy peptide-induced phosphorylation of the ERK/mTOR/S6RP/eIF4E pathway was blocked in response to pretreatment with PD98059, a specific ERK inhibitor. Moreover, inhibition of TGF-β1 through PD98059 pretreatment and a consecutive decrease in ADSC proliferation revealed that TGF-β1 induces the phosphorylation of mTOR/S6RP/eIF4E. Collectively, the results of this study indicate that ERK-dependent production of TGF-β1 plays a crucial role in the soy peptide-induced proliferation of ADSCs under serum-free conditions.
Copyright © 2011 Elsevier Inc. All rights reserved.
- PMID:
- 22217516
- [PubMed - as supplied by publisher]
Identification in Lupin Seed of a Serine-Endopeptidase Activity Cleaving between Twin Arginine Pairs and Causing Limited Proteolysis of Seed Storage Proteins.
Source
Department of AgriFood Molecular Sciences, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy.
Abstract
The occurrence of twin-arginine motifs (-R-R-) in the amino acid sequences of animal pro-proteins frequently defines the cleavage site(s) for their structural/functional maturation. No information is available on the presence and possible biological meaning of these motifs in the seed storage proteins. In this work, a novel endopeptidase activity with cleavage specificity to twin-arginine pairs has been detected in mature dry Lupinus albus seeds. The endopeptidase was tested with a number of endogenous and exogenous protein substrates, which were selected according to the presence of one or more twin-arginine residue motifs in their amino acid sequences. The observed hydrolysis patterns were limited and highly specific. Partial proteolysis led to stable polypeptide fragments that were characterized by 1- and 2-D electrophoresis. Selected polypeptides were submitted to N-terminal amino acid sequencing and mass spectrometry analyses. These approaches, supported by bioinformatic analysis of the available sequences, allowed the conclusion that the polypeptide cleavage events had occurred at the peptide bonds comprised between twin-arginine residue pairs with all tested protein substrates. The endopeptidase activity was inhibited by 4-(2-AminoEthyl)Benzene-Sulphonyl Fluoride hydrochloride (AEBSF), leupeptin, and serine proteinase protein inhibitors, while it was not affected by pepstatin, trans-Epoxysuccinyl-L-leucylamido(4-guanidino)butane (E64), and ethylenediaminetetraacetic acid (EDTA), thus qualifying the Arg-Arg cleaving enzyme as a serine endopeptidase. The structural features of storage proteins from lupin and other legume seeds strongly support the hypothesis that the occurrence of an endopeptidase activity cleaving -R-R- bonds may be functional to facilitate their degradation at germination and possibly generate polypeptide fragments with specific biological activity.
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