کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1934465 | 1050641 | 2008 | 6 صفحه PDF | دانلود رایگان |
The phospho-PKB/Akt status is often used as surrogate marker to measure activation of the PI3K/Akt/mTOR signal transduction pathway. Though, inconsistencies of the p-Ser473-PKB/Akt status have raised doubts in the validity of p-Ser473-PKB/Akt phosphorylation as endpoint. Here, we determined that p-Ser473-PKB/Akt but not p-Thr308-PKB/Akt phosphorylation is highly temperature sensitive. p-Ser473-PKB/Akt phosphorylation was rapidly reduced to levels below 50% on exposure to 20–25 °C in murine and human cell lines including cells expressing constitutively active PI3K or lacking PTEN. Down-regulation of p-Ser473-PKB/Akt was reversible and re-exposure to physiological temperature resulted in increased p-Ser473-PKB/Akt phosphorylation levels. Phosphatase activity at low temperature was sustained at 75% baseline level and phosphatase inhibition prevented p-Ser473-PKB/Akt dephosphorylation induced by the low temperature shift. Interestingly temperature-dependent deregulation of the p-Ser473-PKB/Akt status was also observed in response to irradiation. Thus our data demonstrate that minimal additional stress factors deregulate the PI3K/Akt-survival pathway and the p-Ser473-PKB/Akt status as experimental endpoint.
Journal: Biochemical and Biophysical Research Communications - Volume 375, Issue 3, 24 October 2008, Pages 399–404