Interaction of Akt-phosphorylated SRPK2 with 14-3-3 Mediates Cell Cycle and Cell Death in Neurons

• Published in: The Journal of biological chemistry Vol. 284; no. 36; pp. 24512 - 24525
• Main Authors: Jang, Sung-Wuk, Liu, Xia, Fu, Haian, Rees, Howard, Yepes, Manuel, Levey, Allan, Ye, Keqiang
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04.09.2009; American Society for Biochemistry and Molecular Biology
• Subjects: 14-3-3 Proteins - genetics; 14-3-3 Proteins - metabolism; Animals; Apoptosis; Brain Ischemia - genetics; Brain Ischemia - metabolism; Cell Cycle; Cell Survival - genetics; Cyclin D1 - genetics; Cyclin D1 - metabolism; HeLa Cells; Humans; Male; Mechanisms of Signal Transduction; Mice; Neurons - metabolism; Phosphatidylinositol 3-Kinases - genetics; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation; Protein Binding; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; Up-Regulation - genetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M109.026237

Terminally differentiated neurons are unable to reenter the cell cycle. Aberrant cell cycle activation provokes neuronal cell death, whereas cell cycle inhibition elevates neuronal survival. However, the molecular mechanism regulating the cell cycle and cell death in mature neurons remains elusive. Here we show that SRPK2, a protein kinase specific for the serine/arginine (SR) family of splicing factors, triggers cell cycle progression in neurons and induces apoptosis through regulation of nuclear cyclin D1. Akt phosphorylates SRPK2 on Thr-492 and promotes its nuclear translocation leading to cyclin D1 up-regulation, cell cycle reentry, and neuronal apoptosis. In addition, SRPK2 phosphorylates SC35 and, thus, inactivates p53, resulting in cyclin D1 up-regulation. 14-3-3 binding to SRPK2, regulated by Akt phosphorylation, inhibits these events. We find that SRPK2 is phosphorylated in ischemia-attacked brain, correlating with the observed increase in cyclin D1 levels. Hence, phosphatidylinositol 3-kinase/Akt mediates the cell cycle and cell death machinery in the nervous system through phosphorylation of SRPK2.