-containing fractions were dialyzed and stored at ?80C. Heat Shock. antibodies tested showed dephosphorylation at 0 h and hyperphosphorylation at 3C6 h, Prostaglandin E2 except for 12E8, which showed hyperphosphorylation also at 0 h. Immunoblot analysis using activity-dependent antibodies against ERK1/2, JNK, and GSK-3 confirmed the above data. Increased activation and inhibition of kinases after warmth shock were statistically significant in comparison with controls. Because is usually hyperphosphorylated in Alzheimer disease these findings suggest that JNK, GSK-3, and Cdk5 may play a role in its pathogenesis. The cause of Alzheimer disease (AD) is not known, but it appears to be a syndrome resulting from an interplay of a genetic predisposition, environmental stress factors, and the aging process. Specific genetic defects have been recognized around the genes of presenilins 1 and 2 and amyloid precursor protein, but familial AD accounts for less than 5% of all cases (1). Recently, mutations of the gene have been explained in a group of neurodegenerative dementias (2), but no mutations of the gene have been found in AD. The histologic hallmarks of AD are the senile plaques made of extracellular A amyloid and dystrophic neurites and the intraneuronal neurofibrillary tangles (NFT) composed of bundles of abnormal filaments, the so-called paired helical filaments (PHF) and Rabbit Polyclonal to XRCC1 the related straight filaments, the major component of which is usually hyperphosphorylated (3C5). However, the earliest manifestation of hyperphosphorylated is usually a granular form in the Prostaglandin E2 somatodendritic compartment (4, 5). Normal fetal and adult brain are groups of multiply phosphorylated and thermostable proteins generated by option splicing of exons 2 and 3 in the amino-terminal region and exon 10 in the microtubule-binding region Prostaglandin E2 of the single gene located on chromosome 17q21 (2, 6). Thus, six human (7, 8), four bovine (8, 9), and three rat (8, 10) isoforms are generated. Bovine isoforms contain either 3 or 4 4 repeats and 1 or 2 2 amino-terminal inserts. All three adult rat isoforms contain 4 repeats and 0, 1, or 2 amino-terminal inserts. In attempts to create animal models of AD, transgenic mouse models overexpressing 3- or 4-repeat isoforms have been developed (11, 12), but the results were rather disappointing because axonal swellings were the main abnormality. These swellings are reminiscent of the ,-iminodipropionitrile intoxication, where distal dissociation of microtubules from neurofilaments precedes the formation of proximal axonal swellings (13), suggesting that overexpressed interferes with the microtubuleCneurofilament interactions. Although original studies localized only in axons (14), was subsequently also found in the somatodendritic compartment and in glial cells (15). Thus, mere localization of in the somatodendritic compartment should not be considered pathological. However, in a transgenic mouse model of frontotemporal dementia and parkinsonism linked to chromosome 17 expressing P301L mutant , NFT were found mostly in infratentorial brain and spinal cord but not in cerebral cortex and hippocampus (16). Although many kinases and phosphatases have been shown to take action on (17), the dysregulated processes of dephosphorylationChyperphosphorylation that lead to PHF- are not known. However, after studying the morphology, development, and distribution of immunoreactivity in AD we suggested that it could represent a defensive response to numerous nerve-racking stimuli, either endogenous or exogenous (4, 5). To test this hypothesis, we have shown by using the anti- antibodies Tau-1 and PHF-1 that warmth shock induces quick dephosphorylation followed by hyperphosphorylation of in female rats that is much like PHF- in AD (18, 19), and androgens, but not estrogens, prevent the warmth shock-induced hyperphosphorylation of (20, 21). The relevance of this model to AD is usually further enhanced by the many studies that show a stress response in AD brain (22, 23). In this study, to characterize further this rat warmth shock model, we investigated in immunocomplex kinase assays the activities of extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun NH2-terminal kinase (JNK), glycogen synthase kinase-3 (GSK-3), cyclin-dependent kinase 5 (Cdk5), cAMP-dependent protein kinase (PKA),.