Abstract
Inhibitor-1 becomes a potent inhibitor of protein phosphatase 1 when phosphorylated by cAMP-dependent protein kinase at Thr35. Moreover, Ser67 of inhibitor-1 serves as a substrate for cyclin-dependent kinase 5 in the brain. Here, we report that dephosphoinhibitor-1 but not phospho-Ser67 inhibitor-1 was efficiently phosphorylated by protein kinase C at Ser65 in vitro. In contrast, Ser67 phosphorylation by cyclin-dependent kinase 5 was unaffected by phospho-Ser 65. Protein kinase C activation in striatal tissue resulted in the concomitant phosphorylation of inhibitor-1 at Ser65 and Ser 67, but not Ser65 alone. Selective pharmacological inhibition of protein phosphatase activity suggested that phospho-Ser 65 inhibitor-1 is dephosphorylated by protein phosphatase 1 in the striatum. In vitro studies confirmed these findings and suggested that phospho-Ser67 protects phospho-Ser65 inhibitor-1 from dephosphorylation by protein phosphatase 1 in vivo. Activation of group I metabotropic glutamate receptors resulted in the up-regulation of diphospho-Ser65/Ser67 inhibitor-1 in this tissue. In contrast, the activation of N-methyl-D-aspartate-type ionotropic glutamate receptors opposed increases in striatal diphospho-Ser65/Ser 67 inhibitor-1 levels. Phosphomimetic mutation of Ser65 and/or Ser67 did not convert inhibitor-1 into a protein phosphatase 1 inhibitor. On the other hand, in vitro and in vivo studies suggested that diphospho-Ser65/Ser67 inhibitor-1 is a poor substrate for cAMP-dependent protein kinase. These observations extend earlier studies regarding the function of phospho-Ser67 and underscore the possibility that phosphorylation in this region of inhibitor-1 by multiple protein kinases may serve as an integrative signaling mechanism that governs the responsiveness of inhibitor-1 to cAMP-dependent protein kinase activation.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 24322-24335 |
| Number of pages | 14 |
| Journal | Journal of Biological Chemistry |
| Volume | 281 |
| Issue number | 34 |
| DOIs | |
| State | Published - Aug 25 2006 |
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ASJC Scopus subject areas
- Biochemistry
Cite this
Phosphorylation of protein phosphatase inhibitor-1 by protein kinase C. / Sahin, Bogachan; Shu, Hongjun; Fernandez, Joseph; El-Armouche, Ali; Molkentin, Jeffery D.; Nairn, Angus C.; Bibb, James A.
In: Journal of Biological Chemistry, Vol. 281, No. 34, 25.08.2006, p. 24322-24335.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Phosphorylation of protein phosphatase inhibitor-1 by protein kinase C
AU - Sahin, Bogachan
AU - Shu, Hongjun
AU - Fernandez, Joseph
AU - El-Armouche, Ali
AU - Molkentin, Jeffery D.
AU - Nairn, Angus C.
AU - Bibb, James A.
PY - 2006/8/25
Y1 - 2006/8/25
N2 - Inhibitor-1 becomes a potent inhibitor of protein phosphatase 1 when phosphorylated by cAMP-dependent protein kinase at Thr35. Moreover, Ser67 of inhibitor-1 serves as a substrate for cyclin-dependent kinase 5 in the brain. Here, we report that dephosphoinhibitor-1 but not phospho-Ser67 inhibitor-1 was efficiently phosphorylated by protein kinase C at Ser65 in vitro. In contrast, Ser67 phosphorylation by cyclin-dependent kinase 5 was unaffected by phospho-Ser 65. Protein kinase C activation in striatal tissue resulted in the concomitant phosphorylation of inhibitor-1 at Ser65 and Ser 67, but not Ser65 alone. Selective pharmacological inhibition of protein phosphatase activity suggested that phospho-Ser 65 inhibitor-1 is dephosphorylated by protein phosphatase 1 in the striatum. In vitro studies confirmed these findings and suggested that phospho-Ser67 protects phospho-Ser65 inhibitor-1 from dephosphorylation by protein phosphatase 1 in vivo. Activation of group I metabotropic glutamate receptors resulted in the up-regulation of diphospho-Ser65/Ser67 inhibitor-1 in this tissue. In contrast, the activation of N-methyl-D-aspartate-type ionotropic glutamate receptors opposed increases in striatal diphospho-Ser65/Ser 67 inhibitor-1 levels. Phosphomimetic mutation of Ser65 and/or Ser67 did not convert inhibitor-1 into a protein phosphatase 1 inhibitor. On the other hand, in vitro and in vivo studies suggested that diphospho-Ser65/Ser67 inhibitor-1 is a poor substrate for cAMP-dependent protein kinase. These observations extend earlier studies regarding the function of phospho-Ser67 and underscore the possibility that phosphorylation in this region of inhibitor-1 by multiple protein kinases may serve as an integrative signaling mechanism that governs the responsiveness of inhibitor-1 to cAMP-dependent protein kinase activation.
AB - Inhibitor-1 becomes a potent inhibitor of protein phosphatase 1 when phosphorylated by cAMP-dependent protein kinase at Thr35. Moreover, Ser67 of inhibitor-1 serves as a substrate for cyclin-dependent kinase 5 in the brain. Here, we report that dephosphoinhibitor-1 but not phospho-Ser67 inhibitor-1 was efficiently phosphorylated by protein kinase C at Ser65 in vitro. In contrast, Ser67 phosphorylation by cyclin-dependent kinase 5 was unaffected by phospho-Ser 65. Protein kinase C activation in striatal tissue resulted in the concomitant phosphorylation of inhibitor-1 at Ser65 and Ser 67, but not Ser65 alone. Selective pharmacological inhibition of protein phosphatase activity suggested that phospho-Ser 65 inhibitor-1 is dephosphorylated by protein phosphatase 1 in the striatum. In vitro studies confirmed these findings and suggested that phospho-Ser67 protects phospho-Ser65 inhibitor-1 from dephosphorylation by protein phosphatase 1 in vivo. Activation of group I metabotropic glutamate receptors resulted in the up-regulation of diphospho-Ser65/Ser67 inhibitor-1 in this tissue. In contrast, the activation of N-methyl-D-aspartate-type ionotropic glutamate receptors opposed increases in striatal diphospho-Ser65/Ser 67 inhibitor-1 levels. Phosphomimetic mutation of Ser65 and/or Ser67 did not convert inhibitor-1 into a protein phosphatase 1 inhibitor. On the other hand, in vitro and in vivo studies suggested that diphospho-Ser65/Ser67 inhibitor-1 is a poor substrate for cAMP-dependent protein kinase. These observations extend earlier studies regarding the function of phospho-Ser67 and underscore the possibility that phosphorylation in this region of inhibitor-1 by multiple protein kinases may serve as an integrative signaling mechanism that governs the responsiveness of inhibitor-1 to cAMP-dependent protein kinase activation.
UR - http://www.scopus.com/inward/record.url?scp=33747675454&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33747675454&partnerID=8YFLogxK
U2 - 10.1074/jbc.M603282200
DO - 10.1074/jbc.M603282200
M3 - Article
VL - 281
SP - 24322
EP - 24335
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 34
ER -