Phosphorylation and activation of nuclear Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) by Ca2+/calmodulin-dependent protein kinase I (CaMKI)
- 作者：Takashi Onouchia ; Noriyuki Sueyoshia ; sueyoshi@ag.kagawa-u.ac.jp ; Atsuhiko Ishidab ; Isamu Kameshitaa
- 关键词：CaM ; calmodulin ; CaMK ; Ca2+/calmodulin-dependent protein kinase ; CaMKP-N ; nuclear Ca2+/calmodulin-dependent protein kinase phosphatase ; MUP ; 4-methylumbelliferyl phosphate ; NLS ; nuclear localization signal
- 刊名：Biochemical and Biophysical Research Communications
- 出版年：2012
- 期刊代码：159_0006291x
- 类别：bio
- 出版时间：15 June, 2012
- 卷：422
- 期：4
- 页码：703-709
- 文件大小：433 K
摘要
Nuclear Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) is an enzyme that dephosphorylates and downregulates multifunctional Ca2+/calmodulin-dependent protein kinases (CaMKs) as well as AMP-dependent protein kinase. In our previous study, we found that zebrafish CaMKP-N (zCaMKP-N) underwent proteolytic processing and translocated to cytosol in a proteasome inhibitor-sensitive manner. In the present study, we found that zCaMKP-N is regulated by phosphorylation at Ser-480. When zCaMKP-N was incubated with the activated CaMKI, time-dependent phosphorylation of the enzyme was observed. This phosphorylation was significantly reduced when Ser-480 was replaced by Ala, suggesting that CaMKI phosphorylates Ser-480 of zCaMKP-N. Phosphorylation-mimic mutants, S480D and S480E, showed higher phosphatase activities than those of wild type and S480A mutant in solution-based phosphatase assay using various substrates. Furthermore, autophosphorylation of CaMKII after ionomycin treatment was more severely attenuated in Neuro2a cells when CaMKII was cotransfected with the phosphorylation-mimic mutant of zCaMKP-N than with the wild-type or non-phosphorylatable zCaMKP-N. These results strongly suggest that phosphorylation of zCaMKP-N at Ser-480 by CaMKI activates CaMKP-N catalytic activity and thereby downregulates multifunctional CaMKs in the cytosol.