Regulation of ER-associated Degradation by Akt and Biochemical Analysis of SIK2
Date Issued
2008
Date
2008
Author(s)
Liu, Shang-Yun
Abstract
The purpose of this study is to investigate the regulatory role for Akt in ER-associated degradation, and other molecular characters of SIK2. SIK2 has been demonstrated to promote ER-associated degradation (ERAD) in our lab. Here we found that Akt negatively regulates ERAD. Treatment with Akt inhibitor VIII or overexpression of dominant negative Akt resulted in the accelerated degradation rate on CD3δ, a known substrate for ERAD, and enhanced SIK2 kinase activity in 293T cells. SIK2 was phosphorylated by Akt at Ser358 in vitro, and was associated with Akt in cells. The mutated SIK2 (S358A) comprised stronger kinase activity, and faster degradation rate on CD3δ was observed in cells expressing mutated SIK2 (S358A). These results suggest that Akt negatively regulates ERAD via phosphorylating SIK2 to repress its kinase activity. In addition, we found SIK2 physically interacts with 14-3-3. Mutations of Ser358 and Ser587 to Ala resulted in the decreased association of SIK2 with 14-3-3. We also found 14-3-3 is an in vitro substrate of SIK2, and binding of 14-3-3 to SIK2 slightly enhanced its kinase activity.
Subjects
ERAD
Akt
SIK2
kinase activity
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