Temperature sensitivity of phospho-Ser(473)-PKB/AKT

Area of Science:

• Cellular signaling
• Molecular biology
• Biochemistry

Background:

• Phospho-PKB/Akt (protein kinase B/Akt) is a key marker for PI3K/Akt/mTOR pathway activation.
• Inconsistencies in p-Ser(473)-PKB/Akt levels raise concerns about its reliability as an experimental endpoint.

Purpose of the Study:

• To investigate the temperature sensitivity of PKB/Akt phosphorylation.
• To determine the impact of environmental factors on PI3K/Akt/mTOR pathway signaling.

Main Methods:

• Assessing p-Ser(473)-PKB/Akt and p-Thr(308)-PKB/Akt phosphorylation levels across different temperatures (20-25°C vs. physiological).
• Utilizing murine and human cell lines, including those with altered PI3K or PTEN status.
• Investigating the role of phosphatases and the effect of irradiation.

Main Results:

• p-Ser(473)-PKB/Akt phosphorylation, but not p-Thr(308)-PKB/Akt, significantly decreased at lower temperatures (20-25°C).
• This downregulation was reversible, with levels returning to baseline upon re-exposure to physiological temperatures.
• Phosphatase activity remained high at low temperatures, contributing to dephosphorylation, and inhibition prevented this effect.

Conclusions:

• The p-Ser(473)-PKB/Akt status is highly sensitive to temperature fluctuations, impacting its utility as a reliable endpoint.
• Minimal stress factors, including temperature shifts and irradiation, can deregulate the PI3K/Akt-survival pathway.
• Researchers should consider environmental conditions when interpreting p-Ser(473)-PKB/Akt phosphorylation data.