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Retinoblastoma protein phosphorylation at multiple sites is associated with neurofibrillary pathology in Alzheimer disease.
MedLine Citation:
PMID:  18784806     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
The re-expression of multiple cell cycle markers representing various cell cycle phases in postmitotic pyramidal neurons suggests that neurons in Alzheimer disease (AD) attempt to re-enter the cell cycle. Entry into the cell cycle requires activation of G1 to S phase cell cycle proteins, among which retinoblastoma protein (pRb) is a key regulator. pRb inhibits the transcription of cell cycle proteins in the nucleus of healthy cells by interaction and consequent blocking of the active site of E2F, dependent upon the phosphate stoichiometry and combination of the locations of their 16 potential phosphorylation sites on pRb. Therefore, to determine whether pRb is involved in the aberrant cell cycle phenotype in AD neurons, a systematic immunocytochemical evaluation of the phosphorylation status of pRb protein using antibodies specific for multiple phosphorylation sites (i.e., pSpT249/252, pS612, pS795, pS807, pS811 and pT821) was carried out in the hippocampal regions of brains from AD patients. Increased levels of phospho-pRb (ppRb) for all these phosphorylation sites were noted in the brains of AD patients as compared to control cases. More importantly, redistribution of ppRb from the nucleus to the cytoplasm of susceptible neurons, with significant localization in neurofibrillary tangles and neuritic plaques, was observed. Additional studies revealed extensive co-localization between phospho-p38 and ppRb, implicating that p38 activation may contribute to cell cycle abnormalities through pRb phosphorylation. Taken together, these data supports the concept of neuronal cell cycle re-entry in AD and indicates a crucial role for pRb in this process.
Authors:
Akanksha Thakur; Sandra L Siedlak; Sheronica L James; David J Bonda; Akanksha Rao; Kate M Webber; Antoni Camins; Mercé Pallàs; Gemma Casadesus; Hyoung-Gon Lee; Robert Bowser; Arun K Raina; George Perry; Mark A Smith; Xiongwei Zhu
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Publication Detail:
Type:  Journal Article     Date:  2008-01-01
Journal Detail:
Title:  International journal of clinical and experimental pathology     Volume:  1     ISSN:  1936-2625     ISO Abbreviation:  Int J Clin Exp Pathol     Publication Date:  2008  
Date Detail:
Created Date:  2008-09-11     Completed Date:  2010-01-21     Revised Date:  2010-09-22    
Medline Journal Info:
Nlm Unique ID:  101480565     Medline TA:  Int J Clin Exp Pathol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  134-46     Citation Subset:  -    
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