| First Author | Shirafuji T | Year | 2014 |
| Journal | J Neurosci | Volume | 34 |
| Issue | 28 | Pages | 9268-80 |
| PubMed ID | 25009260 | Mgi Jnum | J:215306 |
| Mgi Id | MGI:5605100 | Doi | 10.1523/JNEUROSCI.4278-13.2014 |
| Citation | Shirafuji T, et al. (2014) The role of Pak-interacting exchange factor-beta phosphorylation at serines 340 and 583 by PKCgamma in dopamine release. J Neurosci 34(28):9268-80 |
| abstractText | Protein kinase C (PKC) has been implicated in the control of neurotransmitter release. The AS/AGU rat, which has a nonsense mutation in PKCgamma, shows symptoms of parkinsonian syndrome, including dopamine release impairments in the striatum. Here, we found that the AS/AGU rat is PKCgamma-knock-out (KO) and that PKCgamma-KO mice showed parkinsonian syndrome. However, the PKCgamma substrates responsible for the regulated exocytosis of dopamine in vivo have not yet been elucidated. To identify the PKCgamma substrates involved in dopamine release, we used PKCgamma-KO mice and a phosphoproteome analysis. We found 10 candidate phosphoproteins that had decreased phosphorylation levels in the striatum of PKCgamma-KO mice. We focused on Pak-interacting exchange factor-beta (betaPIX), a Cdc42/Rac1 guanine nucleotide exchange factor, and found that PKCgamma directly phosphorylates betaPIX at Ser583 and indirectly at Ser340 in cells. Furthermore, we found that PKC phosphorylated betaPIX in vivo. Classical PKC inhibitors and betaPIX knock-down (KD) significantly suppressed Ca(2+)-evoked dopamine release in PC12 cells. Wild-type betaPIX, and not the betaPIX mutants Ser340 Ala or Ser583 Ala, fully rescued the decreased dopamine release by betaPIX KD. Double KD of Cdc42 and Rac1 decreased dopamine release from PC12 cells. These findings indicate that the phosphorylation of betaPIX at Ser340 and Ser583 has pivotal roles in Ca(2+)-evoked dopamine release in the striatum. Therefore, we propose that PKCgamma positively modulates dopamine release through beta2PIX phosphorylation. The PKCgamma-betaPIX-Cdc42/Rac1 phosphorylation axis may provide a new therapeutic target for the treatment of parkinsonian syndrome. |
