Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.26 (GSK)
 6,788 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Serum and potassium (S/K) deprivation is a well-known apoptotic model in cerebellar granule neurons (CGNs), used to study the efficacy of potential neuroprotective drugs. The objective of this study was to determine the pathways involved in the neuroprotective role of flavopiridol, a pan-inhibitor of cyclin-dependent kinases (CDKs), upon S/K withdrawal-induced apoptosis in CGNs. Cell death in primary cultures of rat CGNs was accompanied by chromatin condensation and activation of caspases-3, -6, and -9. Caspase-3 activity was also evaluated by cleavage of 120-kDa alpha-spectrin. Flavopiridol (1 microM) prevented caspase activation and abolished apoptotic features mediated by S/K withdrawal. Re-entry in the cell cycle is also involved in apoptotic neuronal cell death. Flavopiridol (1 microM) inhibited DNA synthesis as measured by BrdU incorporation, thus enhancing proliferating cell nuclear antigen expression. Serum/potassium (S/K) deprivation induced apoptotic cell death mediated by the activation of several kinases such as glycogen synthase kinase-3beta and CDK5, as well as the breakdown of p35 in the neurotoxic fragment p25; inactivation of myocyte enhancer factor-2 (MEF2) was also found. Pretreatment with flavopiridol prevented these biochemical and molecular alterations. Taken together, these findings suggest an apoptotic route in CGNs after S/K withdrawal mediated by the activation of several kinases involved in cell cycle deregulation and MEF2 inactivation. We propose that the antiapoptotic properties of flavopiridol are mediated through kinase pathway inhibition.
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PMID:Inhibition of multiple pathways accounts for the antiapoptotic effects of flavopiridol on potassium withdrawal-induced apoptosis in neurons. 1596 87

On the basis of previous studies, we identified pyrazine-pyridine A as a potent vascular endothelial growth factor inhibitor and pyrimidine-pyridine B as a moderately potent cyclin dependent kinase (CDK) inhibitor. A proposed combination of CGP-60474 and compound B led to the discovery of [1,3,5]triazine-pyridine as a new series of potent CDK inhibitors. Palladium-catalyzed C-C bond formation reactions, particularly the Negishi coupling reaction, were used to assemble various triazine-heteroaryl analogues effectively. Among them, compound 20 displayed high inhibitory potency at CDK1 (IC(50) = 0.021 microM), CDK2, and CDK5 and submicromolar potency at CDK4, CDK6, and CDK7. Compound 20 also displayed high potency at GSK-3beta. It demonstrated potent antiproliferative activity on various tumor cell lines, including HeLa, HCT-116, U937, and A375. When 20 was administered intraperitoneally at 150 and 125 mg/kg to nude mice bearing human A375 xenografts, the compound produced a significant survival increase. Molecular docking studies were conducted in an attempt to enhance the understanding of the observed structure-activity relationship.
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PMID:Synthesis and identification of [1,3,5]triazine-pyridine biheteroaryl as a novel series of potent cyclin-dependent kinase inhibitors. 1599 92

Several analogues of the 3-substituted-2-oxoindole chemotype were synthesized by condensing isatin or the appropriate haloisatin with some amino acids or histamine under neutral conditions. All the imino derivatives produced were tested for kinase inhibitory properties against three serine/threonine kinases, namely CDK1/cyclin B, CDK5/p25 and GSK3alpha/beta. Most of the histidine derivatives showed inhibitory properties to the three kinases in the low micromolar range. The histamine derivatives were less potent against CDK1/cyclin B and CDK5/p25 and totally inactive against GSK3alpha/beta. So, the management of the carboxyl function may be a tool to impart selectivity in such family of kinases. Docking of 2-[[-5-bromo-2-oxoindolin-3-ylidene]amino]-3-(1H-imidazol2-yl)propanoic acid 14 to CDK5/p25 indicates that this compound can interact with the enzyme through four hydrogen bonds; for GSK/3beta, the ligand poses itself in another orientation, also four hydrogen bonds can be formed between the ligand and the receptor, otherwise hydrophobic interactions seem to predominate. Also, all the final compounds were tested for their in vitro antitumor properties against MCF7 (breast), NCI-H460 (lung) and SF268 (CNS) cancer cell lines. None of the synthesized compounds was cytotoxic at 10(-4) molar concentration. Moreover, compounds 13 and 14 were tested for potential antiangiogenic properties by testing their ability to inhibit the proliferation of human umbilical vein endothelial cells (HUVECs), cord formation and migration in response to chemoattractant. Only compound 14 showed moderate inhibitory properties to HUVECs proliferation and cord formation while its non-brominated derivative 13 did not. Thus, the antiangiogenesis properties are not apparently caused by inhibition of any of the tested kinases.
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PMID:Synthesis of 3-substituted-2-oxoindole analogues and their evaluation as kinase inhibitors, anticancer and antiangiogenic agents. 1649 69

Pyrroloazepinones 8a-j and 9a-j were designed by structural modification of lead compound 3. These compounds were tested on five tumor cell lines to determine the role of the azeto ring and the 2-methyl substituent in the cytotoxicity of compound 3. Our results show that compounds 8a-j (R1=CH3) have dramatically reduced cytotoxicity, resulting from the loss of the azeto moiety of lead compound 3. By contrast, azepinones 9a-j (R1=4-nitrophenyl) inhibited the proliferation of almost all cancer cell lines tested even though they lack the azeto ring. Preliminary SAR studies with these compounds revealed the importance of halogens at the para- or meta-position of the 1-phenyl moiety. Additionally, derivatives 9a (R2=H), 9e (R2=4-F), and 9g (R2=4-OMe) were selectively cytotoxic to U-251 cells. However, none of the pyrroloazepinones inhibited the enzymatic activity of CDK1/cyclin B, CDK5/p25, and GSK-3.
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PMID:Tetrahydropyrrolo[3,2-c]azepin-4-ones as a new class of cytotoxic compounds. 1650 13

In an effort to identify new protein kinase inhibitors with increased potency and selectivity, we have developed the microwave-assisted synthesis of thiazolo[5,4-f]quinazolin-9-ones. The effects of eighteen derivatives on CDK1/cyclin B, CDK5/p25, and GSK-3 were investigated. Several turned out to inhibit GSK-3 in the micromolar range. Molecular modeling studies suggest that the most selective GSK-3 inhibitors 7a-d bind into the ATP-binding site through a key hydrogen bond interaction with Val135 and target the specific hydrophobic backpocket of the enzyme.
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PMID:Thiazolo[5,4-f]quinazolin-9-ones, inhibitors of glycogen synthase kinase-3. 1664 20

In an effort to identify new pharmacological inhibitors of disease-relevant protein kinases with increased potency and selectivity, we synthesized and evaluated new 5-substituted indirubins. The effects of 34 indirubin derivatives on CDK1/cyclin B, CDK5/p25, and GSK-3, as well as on SH-SY5Y human neuroblastoma cell survival, were investigated.
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PMID:Synthesis of novel 5-substituted indirubins as protein kinases inhibitors. 1675 72

Apolipoprotein E (apoE) receptors act as signaling molecules in neurons, altering phosphorylation of numerous proteins after extracellular ligand binding and affecting neurite outgrowth, synapse formation, and neuronal migration. Since apoE is important in the pathogenesis of Alzheimer's disease (AD), we tested whether apoE treatment of neurons affected molecules important to phosphorylation of tau, such as GSK 3beta, P35, and CDK5, and the phosphorylation of tau itself. Treatment of primary neurons with 2 uM apoE (or an apoE-derived peptide) decreased levels of phospho-GSK 3beta, P35 and CDK5, and decreased levels of phosphorylated forms of tau. A lower concentration of apoE (100 nM) had no effect on these molecules. The alteration of tau phosphorylation by apoE was blocked by an inhibitor of the low-density lipoprotein receptor family, demonstrating the effects were due to receptor interactions. These results demonstrate that apoE affects several downstream signaling cascades in neurons: decreased tau kinases phosphorylation and inhibition of tau phosphorylation at Thr171 and Ser202/Thr205 epitopes. We conclude that apoE can alter levels of tau kinases and phospho-tau epitopes, potentially affecting tau neuropathological changes seen in AD brains.
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PMID:Apolipoprotein E decreases tau kinases and phospho-tau levels in primary neurons. 1716 69

Glycogen synthase kinase-3 (GSK-3) is a potential drug target for a number of human diseases. Some indigoids have been found to be potent inhibitors of GSK-3, and individual compounds with better activity, specificity, and solubility are desired. In this work, a new disubstituted indigoid generation system was developed with a tryptophanase-deficient Escherichia coli strain as a host to express the human cytochrome P450 2A6 mutant L240C/N297Q, which catalyzes the oxidation of indole to isatin and indoxyl, which in turn react to generate indigoids. Forty-five substituted 1H-indoles from commercial sources were used as substrates in the system, and indigoid mixtures were tested as potential inhibitors of GSK-3. After preliminary screening, cell extracts with high inhibitory activity towards GSK-3alpha/beta were fractionated, and the IC50 values of twelve individual indigoids were measured for GSK-3alpha/beta as well as the protein kinases CDK1/cyclinB and CDK5/p25. Several indigoids, including an indigo, showed stronger inhibition than found in previous work. The most potent towards GSK-3alpha/beta, dimethyl indirubin 5,5'-dicarboxylate (IC50 of 51 nM), was modified by chemical reactions. One product, indirubin 5,5'-dicarboxylic acid 5-methyl ester, inhibited GSK-3alpha/beta with an IC50 of 14 nM and selectivity nearly 40-fold over CDK1 and CDK5. Indirubin-5-5'-dicarbonitrile was also modified to the corresponding 3'-oxime, which had low specificity but showed very high inhibition of all three kinases with IC50 values of 5, 13, and 10 nM towards GSK-3alpha/beta, CDK1, and CDK5, respectively. Thus, this system has the potential to generate new indigoids with therapeutic potential.
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PMID:Biosynthesis of new indigoid inhibitors of protein kinases using recombinant cytochrome P450 2A6. 1719 19

Although GSK-3 activity can be regulated by phosphorylation and through interaction with GSK-3-binding proteins, here we describe N-terminal proteolysis as a novel way to regulate GSK-3. When brain extracts were exposed to calcium, GSK-3 was truncated, generating two fragments of approximately 40 and 30 kDa, a proteolytic process that was inhibited by specific calpain inhibitors. Interestingly, instead of inhibiting this enzyme, GSK-3 truncation augmented its kinase activity. When we digested recombinant GSK-3 alpha and GSK-3beta protein with calpain, each isoform was cleaved differently, yet the truncated GSK-3 isoforms were still active kinases. We also found that lithium, a GSK-3 inhibitor, inhibits full-length and cleaved GSK-3 isoforms with the same IC(50) value. Calpain removed the N-terminal ends of His-tagged GSK-3 isoenzymes, and exposing cultured cortical neurons with ionomycin, glutamate, or N-methyl-d-aspartate led to the truncation of GSK-3. This truncation was blocked by the calpain inhibitor calpeptin, at the same concentration at which it inhibits calpain-mediated cleavage of NMDAR-2B and of p35 (the regulatory subunit of CDK5). Together, our data demonstrate that calpain activation produces a truncation of GSK-3 that removes an N-terminal inhibitory domain. Furthermore, we show that GSK-3 alpha and GSK-3beta isoenzymes have a different susceptibility to this cleavage, suggesting a means to specifically regulate these isoenzymes. These data provide the first direct evidence that calpain promotes GSK-3 truncation in a way that has implications in signal transduction, and probably in pathological disorders such as Alzheimer disease.
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PMID:N-terminal cleavage of GSK-3 by calpain: a new form of GSK-3 regulation. 1756 62

Neurofibromatosis type 1 (NF1) tumor suppressor gene product, neurofibromin, functions in part as a Ras-GAP, a negative regulator of Ras. Neurofibromin is implicated in the neuronal abnormality of NF1 patients; however, the precise cellular function of neurofibromin has yet to be clarified. Using proteomic strategies, we identified a set of neurofibromin-associating cellular proteins, including axon regulator CRMP-2 (Collapsin response mediator protein-2). CRMP-2 directly bound to the C-terminal domain of neurofibromin, and this association was regulated by the manner of CRMP-2 phosphorylation. In nerve growth factor-stimulated PC12 cells, neurofibromin and CRMP-2 co-localized particularly on the distal tips and branches of extended neurites. Suppression of neurofibromin using NF1 small interfering RNA significantly inhibited this neurite outgrowth and up-regulated a series of CRMP-2 phosphorylations by kinases identified as CDK5, GSK-3b, and Rho kinase. Overexpression of the NF1-RAS-GAP-related domain rescued these NF1 small interfering RNA-induced events. Our results suggest that neurofibromin regulates neuronal differentiation by performing one or more complementary roles. First, neurofibromin directly regulates CRMP-2 phosphorylation accessibility through the complex formation. Also, neurofibromin appears to indirectly regulate CRMP-2 activity by suppressing CRMP-2-phosphorylating kinase cascades via its Ras-GAP function. Our study demonstrates that the functional association of neurofibromin and CRMP-2 is essential for neuronal cell differentiation and that lack of expression or abnormal regulation of neurofibromin can result in impaired function of neuronal cells, which is likely a factor in NF1-related pathogenesis.
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PMID:Neurofibromatosis type 1 (NF1) tumor suppressor, neurofibromin, regulates the neuronal differentiation of PC12 cells via its associating protein, CRMP-2. 1821 17


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