Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly(L-glutamic acid) (PGA)-cystamine-[gadolinium (Gd)-DO3A] was prepared in high yield with a high Gd-DO3A conjugation efficiency. Approximately 55% of the carboxylic groups in PGA were loaded with Gd-DO3A via cystamine as the spacer. Cystamine can be readily cleaved by endogenous thiols to release the Gd(III) chelates from the conjugate facilitating Gd(III) excretion after the magnetic resonance imaging (MRI). The contrast-enhanced MRI with PGA-cystamine-(Gd-DO3A) was investigated in mice bearing MDA-MB-231 breast carcinoma xenografts. PGA-1,6-hexanediamine-(Gd-DO3A), a paramagnetic polymer conjugate of a nondegradable spacer, was used as a control. Both conjugates resulted in similar contrast enhancement in the heart, vasculature, liver and kidneys in the first hour post injection. More substantial signal intensity reduction was observed for PGA-cystamine-(Gd-DO3A) in these organs than PGA-1,6-hexanediamine-(Gd-DO3A) due to release of the Gd chelates from PGA-cystamine-(Gd-DO3A) after the cleavage of the disulfide spacer by the endogenous thiols. Both conjugates resulted in similar tumor enhancement with approximately 70% increased signal intensity in the tumor periphery and 10-40% increased signal intensity in tumor interstitium. No cross-reaction was observed between PGA-cystamine-(Gd-DO3A) and human serum albumin, a plasma protein containing a cysteine residue. PGA-cystamine-(Gd-DO3A) resulted in significantly lower Gd(III) tissue retention than PGA-1,6-hexanediamine-(Gd-DO3A) 10 days after the injection in the mice (P<.05). The conjugation of Gd(III) chelates to biomedical copolymers via the degradable disulfide spacer resulted in significant contrast enhancement in the blood pool and tumor tissue but minimal long-term Gd(III) tissue retention.
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PMID:Biodegradable cystamine spacer facilitates the clearance of Gd(III) chelates in poly(glutamic acid) Gd-DO3A conjugates for contrast-enhanced MR imaging. 1691 10

Pathophysiological processes associated with oxidative stress lead to the generation of reactive lipid species. Among them, lipids bearing unsaturated aldehyde or ketone moieties can form covalent adducts with cysteine residues and modulate protein function. Through proteomic techniques we have identified actin as a target for the addition of biotinylated analogs of the cyclopentenone prostaglandins 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) and PGA(1) in NIH-3T3 fibroblasts. This modification could take place in vitro and mapped to the protein C-terminal end. Other electrophilic lipids, like the isoprostane 8-iso-PGA(1) and 4-hydroxy-2-nonenal, also bound to actin. The C-terminal region of actin is important for monomer-monomer interactions and polymerization. Electron microscopy showed that actin treated with 15d-PGJ(2) or 4-hydroxy-2-nonenal formed filaments which were less abundant and displayed shorter length and altered structure. Streptavidin-gold staining allowed mapping of biotinylated 15d-PGJ(2) at sites of filament disruption. These results shed light on the structural implications of actin modification by lipid electrophiles.
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PMID:Addition of electrophilic lipids to actin alters filament structure. 1697 89

Prostanoids with cyclopentenone structure (cyP) display a potent anti-inflammatory and antiproliferative activity. CyP are reactive compounds, which may modulate cellular functions by multiple mechanisms, including the direct covalent modification of cysteine residues by Michael addition. This interaction displays selectivity since only a subset of cellular proteins is modified by cyP. Several factors have been proposed to influence the selectivity and/or extent of cyP addition to proteins, including determinants related to protein and cyP structure, and levels of cellular thiols, such as glutathione (GSH). Here we have explored the ability of biotinylated cyP analogs to modify several recombinant proteins in vitro, and the influence of GSH in these effects. We have observed that protein modification by cyP is protein- and cyP-selective. Under our conditions, biotinylated 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)-B) was more efficient than biotinylated PGA(1) (PGA(1)-B) at forming adducts with components of the transcription factors NF-kappaB and activator protein-1 (AP-1). However, both biotinylated cyP were nearly equipotent at modifying human GSTP1-1. Interestingly, the presence of GSH differentially modulated the formation of protein-cyP adducts. Under our conditions, GSH reduced the incorporation of cyP into GST, but improved their binding to p50, more intensely in the case of PGA(1)-B. These results evidence the importance of GSH-cyP and/or GSH-protein interactions for the selectivity of protein modification by cyP and suggest a complex role for GSH that may be related to its ability to prevent protein oxidation or induce conformational alterations. This may shed light on the factors involved in the pleiotropic effects of electrophiles with therapeutic potential.
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PMID:Modification of proteins by cyclopentenone prostaglandins is differentially modulated by GSH in vitro. 1740 18

Prostaglandins with cyclopentenone structure (cyPG) display potent antiproliferative actions that have elicited their study as potential anticancer agents. Several natural and synthetic analogs of the cyPG prostaglandin A(1) (PGA(1)) have proven antitumoral efficacy in cancer cell lines and animal models. In addition, PGA(1) has been used as an inhibitor of transcription factor NF-kappaB-mediated processes, including inflammatory gene expression and viral replication. An important determinant for these effects is the ability of cyPG to form Michael adducts with free thiol groups. The chemical nature of this interaction implies that PGA(1) could covalently modify cysteine residues in a large number of cellular proteins potentially involved in its beneficial effects. However, only a few targets of PGA(1) have been identified. In previous work, we have observed that a biotinylated analog of PGA(1) that retains the cyclopentenone moiety (PGA(1)-B) binds to multiple targets in fibroblasts. Here, we have addressed the identification of these targets through a proteomic approach. Cell fractionation followed by avidin affinity chromatography yielded a fraction enriched in proteins modified by PGA(1)-B. Analysis of this fraction by SDS-PAGE and LC-MS/MS allowed the identification of the chaperone Hsp90, elongation and initiation factors for protein synthesis and cytoskeletal proteins including actin, tubulin and vimentin. Furthermore, we have characterized the modification of vimentin both in vitro and in intact cells. Our observations indicate that cysteine 328 is the main site for PGA(1) addition. These results may contribute to a better understanding of the mechanism of action of PGA(1) and the potential of cyPG-based therapeutic strategies.
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PMID:Study of protein targets for covalent modification by the antitumoral and anti-inflammatory prostaglandin PGA1: focus on vimentin. 1796 May 81

Pepsin from the stomach of albacore tuna, skipjack tuna, and tongol tuna was characterized. Pepsin from all tuna species showed maximal activity at pH 2.0 and 50 degrees C when hemoglobin was used as a substrate. Among the stomach extract of all species tested, that of albacore tuna showed the highest activity (40.55 units/g tissue) (P < 0.05). Substrate-Native-PAGE revealed that pepsin from albacore tuna and tongol tuna consisted of 2 isoforms, whereas pepsin from skipjack tuna had only 1 form. The activity was completely inhibited by pepstatin A, while EDTA (ethylenediaminetetraacetic acid), SBTI (soybean trypsin inhibitor), and E-64 (1-(L-trans-epoxysuccinyl-leucylamino)-4-guanidinobutane) exhibited negligible effect. The activity was strongly inhibited by SDS (sodium dodecyl sulfate) (0.05% to 0.1%, w/v). Cysteine (5 to 50 mM) also showed an inhibitory effect in a concentration dependent manner. ATP, molybdate, NaCl, MgCl(2), and CaCl(2) had no impact on the activity. When tuna pepsin (10 units/g defatted skin) was used for collagen extraction from the skin of threadfin bream for 12 h, the yield of collagen increased by 1.84- to 2.32-fold and albacore pepsin showed the comparable extraction efficacy to porcine pepsin. The yield generally increased with increasing extraction time (P < 0.05). All collagen obtained with the aid of tuna pepsin showed similar protein patterns compared with those found in acid-solubilized collagen. Nevertheless, pepsin from skipjack tuna caused the degradation of alpha and beta components. All collagens were classified as type I with large portion of beta-chain. However, proteins with molecular weight (MW) greater than 200 kDa were abundant in acid-solubilized collagen.
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PMID:Tuna pepsin: characteristics and its use for collagen extraction from the skin of threadfin bream (Nemipterus spp.). 1857 87

Novel water-insoluble, and reduction-responsive nonwoven scaffolds were fabricated from gamma-PGA and tested in cell culture. An electrospinning method was developed to produce scaffolds of fibers with diameters of 0.05-0.5 microm. Crosslinking of the fibers with cystamine in the presence of EDC resulted in water-insoluble gamma-PGA nonwovens with disulfide crosslinkages. These crosslinked fibers were easily decomposed under physiological conditions using L-cysteine, a biocompatible reductant. In vitro experiments with mouse L929 fibroblasts showed good adhesion onto gamma-PGA-SS fiber matrices and excellent cell proliferation. These gamma-PGA-SS nonwovens can be used as novel biocompatible and biodegradable scaffolds with reduction-responsiveness for biomedical or tissue engineering applications.
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PMID:Disulfide-crosslinked electrospun poly(gamma-glutamic acid) nonwovens as reduction-responsive scaffolds. 1937 Jul 50

The cyclopentenone prostaglandin (cyPG) PGA(1) displays potent anti-proliferative and anti-inflammatory effects. Therefore, PGA(1) derivatives are being studied as therapeutic agents. One major mechanism for cyPG action is the modification of protein cysteine residues, the nature of the modified proteins being highly dependent on the structure of the cyPG. Biotinylated cyPGs may aid in the proteomic identification of cyPG targets of therapeutic interest. However, for the identified targets to be relevant it is critical to assess whether biotinylated cyPGs retain the desired biological activity. Here we have explored the anti-inflammatory, anti-proliferative and cell stress-inducing effects of a biotinylated analog of PGA(1) (PGA(1)-biotinamide, PGA(1)-B), to establish its validity to identify cyPG-protein interactions of potential therapeutic interest. PGA(1) and PGA(1)-B displayed similar effects on cell viability, Hsp70 and heme oxygenase-1 induction and pro-inflammatory gene inhibition. Remarkably, PGA(1)-B did not activate PPAR. Therefore, this biotinylated analog can be useful to identify PPAR-independent effects of cyPGs. Protein modification and subcellular distribution of PGA(1)-B targets were cell-type-dependent. Through proteomic and biochemical approaches we have identified a novel set of PGA(1)-B targets including proteins involved in stress response, protein synthesis, cytoskeletal regulation and carbohydrate metabolism. Moreover, the modification of several of the targets identified could be reproduced in vitro. These results unveil novel interactions of PGA(1) that will contribute to delineate the mechanisms for the anti-proliferative and metabolic actions of this cyPG.
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PMID:A biotinylated analog of the anti-proliferative prostaglandin A1 allows assessment of PPAR-independent effects and identification of novel cellular targets for covalent modification. 1980 Mar 25

The following experimental results have been obtained. 1. Native egg albumin treated with iodine and then denatured no longer gives a nitroprusside test or reduces dilute ferricyanide in neutral Duponol PC solution. 2. More iodine is needed to abolish the ferricyanide reduction if the reaction between native egg albumin and iodine is carried out at pH 6.8 than if the reaction is carried out at pH 3.2. At pH 6.8 iodine reacts with tyrosine as well as with cysteine. 3. Cysteine and tryptophane are the only amino acids with reducing groups which are known to react with dilute iodine at pH 3.2 The reducing power of cysteine is abolished by the reaction with iodine, whereas the reducing power of tryptophane remains intact. Pepsin and chymotrypsinogen which contain tryptophane but not cysteine, do not react at all with dilute iodine at pH 3.2. 4. Native egg albumin treated with iodoacetamide at pH 9.0 and then denatured by Duponol PC reduces only 60 per cent as much dilute ferricyanide as egg albumin which has not been treated with iodoacetamide. 5. The SH group is the only protein reducing group which is known to react with iodoacetamide. The simplest explanation of the new observation that the SH groups of egg albumin can be modified by reactions with the native form of the protein is that the native egg albumin has free and accessible but relatively unreactive SH groups which can react with iodine and iodoacetamide despite the fact that they do not react with ferricyanide, porphyrindin, or nitroprusside. Preliminary experiments suggested by the results with egg albumin indicate that the tobacco mosaic virus is modified by iodine at pH 2.8 without being inactivated and that the tobacco mosaic and rabbit papilloma viruses are not inactivated by iodoacetamide at pH 8.0.
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PMID:THE REACTIONS OF IODINE AND IODOACETAMIDE WITH NATIVE EGG ALBUMIN. 1987 58

HL-60 cells treated by prostaglandin (PG) A(2) showed characteristics of apoptosis such as accumulation of hypodiploid and annexin V positive cells, condensed and fragmented nuclei, cytochrome c (Cyt C) release from mitochondria and activation of caspase-1, -2, -3, -7 and -9. PGA(2)-induced cell death was rescued by inhibitors of caspase-9 and -3, but PGA(2)-induced Cyt C release was not prevented by caspase inhibitors. During Cyt C release by PGA(2), mitochondrial transmembrane potential was maintained and mitochondrial permeability transition pore was not formed. In addition, anti-apoptotic BCL-2 family proteins like BCL-2 and BCL-XL, and ROS scavengers including ascorbic acid and 2,2,6,6-tetramethyl-1-piperidinyloxy were not able to inhibit Cyt C release as well as apoptosis by PGA(2). Finally, it was shown that PGA(2)-induced Cyt C release in vitro from purified mitochondria in the absence of cytosolic components. Furthermore, thiol-containing compounds such as N-acetylcysteine, l-cysteine and monothioglycerol prevented Cyt C release, and hence induction of apoptosis. Taken together, these results suggest that PGA(2) activates intrinsic apoptotic pathway by directly stimulating mitochondrial outer membrane permeabilization to release Cyt C, in which thiol-reactivity of PGA(2) plays a pivotal role.
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PMID:Prostaglandin A2 activates intrinsic apoptotic pathway by direct interaction with mitochondria in HL-60 cells. 2004 24

We have previously reported a hydrogel template approach for the construction of centimeter-sized three-dimensional (3D) engineered tissues composed of cultured cells and extracellular matrices (ECM) produced by the cells. However, the interior of the engineered tissues was low in cell density; thus, it was pouched and non-dense morphologies. In this study, we developed thick and highly cell-incorporated engineered tissues by using basic fibroblast growth factor (bFGF) and ascorbic acid 2-phosphate (Asc 2-P). bFGF was loaded into freeze-dried poly(gamma-glutamic acid) hydrogels with disulfide cross-links (gamma-PGA-SS gels) as a template to enhance cell growth. After prescribed times of cell culture, the scaffolds were decomposed by adding a biocompatible reductant, cysteine, and cell proliferation and collagen production were investigated. The loading of bFGF into the scaffolds enhanced cellular invasion and proliferation. Meanwhile, the addition of Asc 2-P to the culture medium induced collagen production from the adhered fibroblasts. However, Asc 2-P did not affect cellular invasion into the template gamma-PGA-SS gels. The volume and weight of the obtained tissues using bFGF after 28 days of culture were 1.3- and 1.4-fold higher than those of control tissues. The thick and highly cell-incorporated 3D-engineered tissues can be useful as a novel cell implantation material for tissue engineering.
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PMID:Development of thick and highly cell-incorporated engineered tissues by hydrogel template approach with basic fibroblast growth factor or ascorbic acid. 2023


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