ABSTRACT
Non-ATP competitive pyrimidine-based inhibitors of CaMKIIdelta were identified. Computational studies were enlisted to predict the probable mode of binding. The results of the computational studies led to the design of ATP competitive inhibitors with optimized hinge interactions. Inhibitors of this class possessed improved enzyme and cellular activity compared to early leads.
Subject(s)
Calcium-Calmodulin-Dependent Protein Kinase Type 2/antagonists & inhibitors , Drug Design , Enzyme Inhibitors/pharmacology , Pyrimidines/pharmacology , Adenosine Triphosphate/metabolism , Binding, Competitive , Enzyme Inhibitors/chemical synthesis , Models, Chemical , Pyrimidines/chemistry , Structure-Activity Relationship , Substrate SpecificityABSTRACT
Apolipoprotein E (ApoE) genotype modulates the risk of Alzheimer's disease. ApoE has been shown essential for amyloid beta-peptide fibrillogenesis and deposition, a defining pathological feature of this disease. Because astrocytes and microglia represent the major source of extracellular apoE in brain, we investigated apoE secretion by glia. We determined that protein prenylation is required for apoE release from a continuous microglial cell line, primary mixed glia, and from organotypic hippocampal cultures. Using selective protein prenylation inhibitors, apoE secretion was found to require protein geranylgeranylation. This prenylation involved a protein critical to apoE secretion, not apoE proper. ApoE secretion could also be suppressed by inhibiting synthesis of mevalonate, the precursor to both types of protein prenylation, using hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors (statins). Recent reports have described the beneficial effects of statins on the risk of dementia. Our finding that protein geranylgeranylation is required for apoE secretion in the brain parenchyma provides another contributing mechanism to explain the effective properties of statins against the development of dementia. In this model, statin-mediated inhibition of mevalonate synthesis, an essential reaction in forming geranylgeranyl lipid, would lower extracellular levels of parenchymal apoE. Because apoE has been found necessary for plaque development in transgenic models of Alzheimer's disease, suppressing apoE secretion by statins could reduce plaques and, in turn, improve cognitive function.
Subject(s)
Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Apolipoproteins E/metabolism , Brain/metabolism , Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology , Lovastatin/analogs & derivatives , Neuroglia/metabolism , Protein Prenylation/physiology , Alkyl and Aryl Transferases/antagonists & inhibitors , Alkyl and Aryl Transferases/metabolism , Alzheimer Disease/physiopathology , Amyloid beta-Peptides/metabolism , Animals , Animals, Newborn , Astrocytes/drug effects , Astrocytes/metabolism , Brain/drug effects , Brain/physiopathology , Cells, Cultured , Disease Models, Animal , Dose-Response Relationship, Drug , Farnesyltranstransferase , Hippocampus/drug effects , Hippocampus/metabolism , Lovastatin/pharmacology , Mevalonic Acid/antagonists & inhibitors , Mevalonic Acid/metabolism , Mice , Mice, Transgenic , Microglia/drug effects , Microglia/metabolism , Neuroglia/drug effects , Polyisoprenyl Phosphates/metabolism , Polyisoprenyl Phosphates/pharmacology , Protein Prenylation/drug effectsABSTRACT
We examined the effect of p38 mitogen-activated protein kinase (MAPK) inhibitors in models of nociception and correlated this effect with localization and expression levels of p38 MAPK in spinal cord. There was a rapid increase in phosphorylated p38 MAPK in spinal cord following intrathecal administration of substance P or intradermal injection of formalin. Immunocytochemistry revealed that phosphorylated p38 MAPK-immunoreactive cells were predominantly present in laminae I-IV of the dorsal horn. Double-staining with markers for neurons, microglia, astrocytes and oligodendrocytes unexpectedly revealed co-localization with microglia but not with neurons or other glia. Pretreatment with p38 MAPK inhibitors (SB20358 or SD-282) had no effect on acute thermal thresholds. However, they attenuated hyperalgesia in several nociceptive models associated with spinal sensitization including direct spinal activation (intrathecal substance P) and peripheral tissue inflammation (intraplantar formalin or carrageenan). Spinal sensitization, manifested by enhanced expression of cyclo-oxygenase-2 and inflammation-induced appearance of Fos-positive neurons, was blocked by pretreatment, but not post-treatment, with p38 MAPK inhibitors. Taken together, these results indicate that spinal p38 MAPK is involved in inflammation-induced pain and that activated spinal microglia play a direct role in spinal nociceptive processing.