Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The pathogenesis of diabetic neuropathy remains unclear, although several factors have been implicated in its pathogenesis. We have examined possible roles of decreased production of nitric oxide, ion channel dysfunction and decreased capacity of nerve regeneration. STZ-induced diabetic rats showed decreases in nociceptive threshold and NADPH-diaphorase positive neurons, nNOS level and cGMP content of DRG at 12 weeks after induction of diabetes. The rats injected by L-NAME, potent nNOS inhibitor, showed decreased nociceptive threshold, although D-NAME, inactive in nNOS inhibition, did not. These results suggest that decreased NO production might be involved in hyperalgesia in diabetic rats. Both hyperglycemia and decreased Na/K-ATPase activity are thought to be characteristic features of diabetic neuropathy. To investigate the presence of ion channel abnormality in diabetic nerves, a Vaseline-gap voltage clamp technique was applied for a single myelinated fibers under 30 mM high glucose plus 0.1 mM ouabain. Since K current was increased, a Ca activated K channel blocker was applied and this increase was shown to be suppressed. Furthermore, Ca channel blockers all suppressed increased K currents, suggesting that the condition induced an increase of Ca influx, thereby increasing Ca activated K currents through K channels. The data are important in that diabetic condition may induce both Ca influx, leading to nerve degeneration, and increased K current, resulting in decreased nerve conduction. Nerve regeneration has been known to be disturbed in diabetic condition. We have shown a decrease in nerve elongation rate in diabetic rats after crush of sciatic nerve, although this decrease was not ameliorated by ARI. Furthermore, Wallerian degeneration was shown to be delayed in diabetic nerves, leading to delayed nerve regeneration. Hyperphosphorylation of both medium and high molecular weight neurofilaments that might be induced by protein kinases including CDK 5 may be involved in the mechanism.
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PMID:[New trend in pathogenesis of diabetic neuropathy]. 1037 17

Flavone acetic acid (FAA) is a synthetic flavonoid that demonstrated extraordinary anti-tumour properties in murine models but was not effective in clinical trials. In an effort to better understand the molecular mechanisms by which FAA asserts its tumouricidal activities, we have examined the effect of FAA on the cell cycle. We observed FAA-mediated G2/M cell cycle arrest in mammary carcinoma cells at a concentration previously demonstrated to have anti-tumour effects in rodent models. The cell cycle arrest was accompanied by an increase in the P34cdc2 (cdc2) cyclin-dependent kinase activity. Morphological cytogenetic analysis demonstrated a colcemid-like effect of FAA on cytokinesis by causing accumulation of condensed C-metaphases of a sustained mitotic block. The cell cycle effect was blocked by the antioxidants ADPC and ascorbate, the superoxide scavenger Tiron, and the sphingosine kinase inhibitor L-cycloserine, but not by inhibitors of nitric oxide synthase. Based on these data, we propose that FAA may induce cell cycle arrest by stimulating the activity of acidic sphingomyelinase leading to the generation of reactive oxygen species.
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PMID:Flavone acetic acid induces a G2/M cell cycle arrest in mammary carcinoma cells. 1047 Oct 38

Previous studies have shown that cerebral hypoxia results in increased tyrosine phosphorylation of cerebral cortical cell membrane proteins as well as nuclear membrane anti-apoptotic protein, Bcl-2. The present study tests the hypothesis that hypoxia results in increased protein tyrosine kinase activity in cortical cell membranes of newborn piglets and that the inhibition of neuronal NOS by administration of 7-nitroindazole sodium salt (7-NINA), a selective inhibitor of nitric oxide synthase (NOS), will prevent the hypoxia-induced increase in protein tyrosine kinase activity. To test this hypothesis, protein tyrosine kinase activity was determined in cerebral cortical membranes of 2- to 4-day-old newborn piglets divided into normoxic (n=6), hypoxic (n=5) and 7-NINA-treated hypoxic (n=5) (7-NINA, 1mg/kg, i.p., prior to hypoxia) groups. Tissue hypoxia was achieved by exposing the animals to an FiO(2) of 0.07 for 60 min and was documented biochemically by determining tissue ATP and phosphocreatine (PCr) levels. Cortical P(2) membranes were isolated and protein tyrosine kinase activity determined by (33)P incorporation into a specific peptide substrate for 15 min at 37 degrees C in a medium containing 100 mM HEPES, pH 7.0, 1mM EDTA, 125 mM MgCl(2), 25 mM MnCl(2), 2mM DTT, 0.2 mM sodium orthovanadate, 2mM EGTA, 150 microM tyrosine kinase peptide substrate [Lys 19] cdc2(6-20)-NH(2), (33)P-ATP, and 10 microg of membrane protein. Protein tyrosine kinase activity was determined by the difference between (33)P incorporation in the presence and absence of specific peptide substrate and expressed as pmol/mg protein/h. The ATP values in the normoxic, hypoxic and 7-NINA-treated hypoxic animals were ATP: 4.57+/-0.45 micromol/g, 1.29+/-0.23 micromol/g (p<0.05 versus normoxic) and 1.50+/-0.14 micromol/g brain (p<0.05 versus normoxic), respectively. The PCr values in the normoxic, hypoxic and 7-NINA-treated hypoxic animals were: 3.77+/-0.36 micromol/g, 0.77+/-0.13 micromol/g (p<0.05 versus normoxic) and 1.02+/-0.24 micromol/g brain (p<0.05 versus normoxic), respectively. Protein tyrosine kinase activity in the normoxic, hypoxic and the 7-NINA-treated groups was 378+/-77 pmol/mg protein/h, 854+/-169 pmol/mg protein/h (p<0.05 versus normoxic) and 464+/-129 pmol/mg protein/h (p<0.05 versus hypoxic), respectively. The data show that cerebral tissue hypoxia results in increased protein tyrosin kinase activity in cortical membranes of newborn piglets and pretreatment with 7-NINA prevents the hypoxia-induced increase in protein tyrosine kinase activity. We conclude that the hypoxia-induced increase in protein tyrosine kinase activity is NO-mediated. We propose that the hypoxia-induced increase in protein tyrosine kinase activity leading to increased phosphorylation of Bcl-2 is a critical link to hypoxic neuronal injury pathway.
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PMID:Effect of hypoxia on protein tyrosine kinase activity in cortical membranes of newborn piglets--the role of nitric oxide. 1553 Oct 99

Tetrahydrobiopterin (BH(4)) has been known to be an essential cofactor for the activities of nitric oxide (NO) synthase and aromatic amino acid hydroxylases, which are involved in physiological and pathological processes. In the present study, we report that sepiapterin, the more stable form of BH4 precursor, modulates vascular endothelial growth factor-A (VEGF-A)-induced cell proliferation and adhesion in human umbilical vein endothelial cells (HUVECs). The antiproliferative activity of sepiapterin in VEGF-A-treated HUVECs is associated with inhibition of the expression of cyclin-dependent kinases (Cdks) such as Cdk4 and Cdk2. Pretreatment with NO synthase inhibitor does not abrogate the ability of sepiapterin to inhibit VEGF-A-induced cell proliferation and adhesion, indicating that the suppressive effects of sepiapterin on VEGF-Ainduced responses are mediated by NO-independent mechanism. Finally, we show that sepiapterin modulates VEGF-A-induced cell proliferation and adhesion through down-regulation of VEGF receptor-2 downstream signaling pathways. Taken together, these findings represent a novel function of sepiapterin in the regulation of angiogenesis, supporting further development and evaluation of sepiapterin as an antiangiogenic agent.
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PMID:Inhibitory effects of sepiapterin on vascular endothelial growth factor-A-induced proliferation and adhesion in human umbilical vein endothelial cells. 2197 20