Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P10636 (tau protein)
 5,110 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Information on the molecular biology of Alzheimer's disease (AD) pointing to new methods of diagnosis and drug therapies is explored. AD is the most common cause of dementia in the elderly and is characterized by senile plaques and neurofibrillary tangles in the brain and loss of cholinergic neurons in the basal forebrain. The disease has a strong genetic component. A definitive diagnosis can be made only by neuropathologic examination at autopsy or biopsy; however, the accuracy of diagnosis based on standard neuropsychological testing and inclusion criteria has improved considerably. Senile plaques consist of a central core of amyloid fibrils surrounded by dystrophic axons. The main component of senile plaque amyloid is a 39-to 42-amino-acid segment referred to as beta-amyloid, which is derived from amyloid precursor protein (APP). APP exists as multiple isoforms encoded by a single gene on chromosome 21. Factors that may influence APP metabolism include activation of phospholipase C, phosphorylation, and the cholinergic system. The microtubule-associated protein tau may contribute to the neurofibrillary tangles of AD. In AD all six adult isoforms of tau can become maximally phosphorylated and can, rather than binding to microtubules, bind to each other, destabilizing the neuronal cytoskeleton. One of the most important discoveries in AD research was the linking of apolipoprotein E phenotype to familial late-onset AD. Acetylcholinesterase inhibitors appear to improve cognitive function but may be limited in utility by adverse effects. Nicotinic agonists are also being investigated as symptomatic therapies. Other possible strategies include nerve growth factor, agents that potentiate the action of endogenous glutamate, antioxidants, nonsteroidal anti-inflammatory drugs, and estrogens. Research into the molecular biology of Alzheimer's disease has begun to point to possible causes of and treatments for this condition.
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PMID:Molecular basis of Alzheimer's disease. 880 75

Glycogen synthase kinase-3 (GSK-3) was generally considered a constitutively active enzyme, only regulated by inhibition. Here we describe that GSK-3 is activated by lysophosphatidic acid (LPA) during neurite retraction in rat cerebellar granule neurons. GSK-3 activation correlates with an increase in GSK-3 tyrosine phosphorylation. In addition, LPA induces a GSK-3-mediated hyperphosphorylation of the microtubule-associated protein tau. Inhibition of GSK-3 by lithium partially blocks neurite retraction, indicating that GSK-3 activation is important but not essential for the neurite retraction progress. GSK-3 activation by LPA in cerebellar granule neurons is neither downstream of Galpha(i) nor downstream of Galpha(q)/phospholipase C, suggesting that it is downstream of Galpha12/13. Overexpression of constitutively active Galpha12 (Galpha12QL) and Galpha13 (Galpha13QL) in Neuro2a cells induces upregulation of GSK-3 activity. Furthermore, overexpression of constitutively active RhoA (RhoAV14) also activates GSK-3 However, the activation of GSK-3 by Galpha13 is blocked by coexpression with C3 transferase, whereas C3 does not block GSK-3 activation by Galpha12. Thus, we demonstrate that GSK-3 is activated by both Galpha12 and Galpha13 in neuronal cells. However, GSK-3 activation by Galpha13 is Rho-mediated, whereas GSK-3 activation by Galpha12 is Rho-independent. The results presented here imply the existence of a previously unknown mechanism of GSK-3 activation by Galpha12/13 subunits.
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PMID:Glycogen synthase kinase-3 is activated in neuronal cells by Galpha12 and Galpha13 by Rho-independent and Rho-dependent mechanisms. 1217 84