| Autor: |
Nishi A; Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan. nishia@med.kurume-u.ac.jp, Bibb JA, Snyder GL, Higashi H, Nairn AC, Greengard P |
| Jazyk: |
angličtina |
| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2000 Nov 07; Vol. 97 (23), pp. 12840-5. |
| DOI: |
10.1073/pnas.220410397 |
| Abstrakt: |
Dopamine and cAMP-regulated phosphoprotein of M(r) 32,000 (DARPP-32) plays an obligatory role in most of the actions of dopamine. In resting neostriatal slices, cyclin-dependent kinase 5 (Cdk5) phosphorylates DARPP-32 at Thr-75, thereby reducing the efficacy of dopaminergic signaling. We report here that dopamine, in slices, and acute cocaine, in whole animals, decreases the state of phosphorylation of striatal DARPP-32 at Thr-75 and thereby removes this inhibitory constraint. This effect of dopamine is achieved through dopamine D1 receptor-mediated activation of cAMP-dependent protein kinase (PKA). The activated PKA, by decreasing the state of phosphorylation of DARPP-32-Thr-75, de-inhibits itself. Dopamine D2 receptor stimulation has the opposite effect. The ability of activated PKA to reduce the state of phosphorylation of DARPP-32-Thr-75 is apparently attributable to increased protein phosphatase-2A activity, with Cdk5 being unaffected. Together, these results indicate that via positive feedback mechanisms, Cdk5 signaling and PKA signaling are mutually antagonistic. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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