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RIC: Research Interest Comparator |
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Affiliation: UT Southwestern
Email: marc.mumby@utsouthwestern.edu
Home Page: http://www4.utsouthwestern.edu/mumbylab/default.htm
Individual subunits of protein phosphatase 2A (PP2A), protein
phosphatase 4, and protein phosphatase 5 were knocked out in
Drosophila Schneider 2 cells by using RNA interference. Ablation of
either the scaffold (A) or catalytic (C) subunits of PP2A caused the
disappearance of all PP2A subunits. Treating cells with doublestranded
RNA targeting all four of the Drosophila PP2A regulatory
subunits caused the disappearance of both the A and C subunits.
The loss of PP2A subunits was associated with decreased protein
stability indicating that only the heterotrimeric forms of PP2A are
stable in intact cells. Ablation of total PP2A by using doublestranded
RNA against either the A or C subunit, or specific ablation
of the R2_B regulatory subunit, enhanced insulin-induced ERK
activation. These results indicated that the R2_B subunit targets
PP2A to the mitogen-activated protein (MAP) kinase cascade in
Schneider 2 cells, where it acts as a negative regulator. A severe
loss of viability occurred in cells in which total PP2A or both
isoforms of the Drosophila R5_B56 subunit had been ablated. The
reduced viability of these cells correlated with the induction of
markers of apoptosis including membrane blebbing and stimulation
of caspase-3-like activity. These observations indicated that
PP2A has a powerful antiapoptotic activity that is specifically
mediated by the R5_B56 regulatory subunits. In contrast to PP2A,
ablation of protein phosphatase 4 caused only a slight reduction in
cell growth but had no effect onMAPkinase signaling or apoptosis.
Depletion of protein phosphatase 5 had no effects on MAP kinase,
cell growth, or apoptosis.
Extraction Method: Keyword Count with Lexical Variants Added-
Eliminated words list: MedlinePlus List
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Similarity Method: Weighted Keyword Count
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Weighting Method: Term Frequency * Inverse Document Frequency
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Database: Medline Updates from current month
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Publication Type: All
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Score Calculation Method: Cosine Similarity Method
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Sort by: Score
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Results computed on: 6/9/2006