AKT and CDK5/p35 Mediate Brain-derived Neurotrophic Factor Induction of DARPP-32 in Medium Size Spiny Neurons in Vitro

• Published in: The Journal of biological chemistry Vol. 282; no. 10; pp. 7352 - 7359
• Main Authors: Bogush, Alexey, Pedrini, Steve, Pelta-Heller, Joshua, Chan, Tung, Yang, Qian, Mao, Zixu, Sluzas, Emily, Gieringer, Tracy, Ehrlich, Michelle E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 09.03.2007; American Society for Biochemistry and Molecular Biology
• Subjects: Androstadienes - pharmacology; Animals; Brain-Derived Neurotrophic Factor - pharmacology; Cells, Cultured; Cyclin-Dependent Kinase 5 - physiology; Dopamine and cAMP-Regulated Phosphoprotein 32 - biosynthesis; Huntington Disease - drug therapy; Mice; Nerve Tissue Proteins - physiology; Neurons - metabolism; Phosphatidylinositol 3-Kinases - physiology; Protein Kinases - physiology; Proto-Oncogene Proteins c-akt - physiology; Rotenone - analogs & derivatives; Rotenone - pharmacology; Signal Transduction; Sirolimus - pharmacology; TOR Serine-Threonine Kinases; Wortmannin
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M606508200

Mature striatal medium size spiny neurons express the dopamine and cyclic AMP-regulated phosphoprotein, 32 kDa (DARPP-32), but little is known about the mechanisms regulating its levels or the specification of fully differentiated neuronal subtypes. Cell extrinsic molecules that increase DARPP-32 mRNA and/or protein levels include brain-derived neurotrophic factor (BDNF), retinoic acid, and estrogen. DARPP-32 induction by BDNF in vitro requires phosphatidylinositide 3-kinase (PI3K), but inhibition of phosphorylation of protein kinase B/Akt does not entirely abolish expression of DARPP-32. Moreover, the requirement for Akt has not been established. Using pharmacologic inhibitors of PI3K, Akt, and cyclin-dependent kinase 5 (cdk5) and constitutively active and dominant negative PI3K, Akt, cdk5, and p35 viruses in cultured striatal neurons, we measured BDNF-induced levels of DARPP-32 protein and/or mRNA. We demonstrated that both the PI3K/Akt/mammalian target of rapamycin and the cdk5/p35 signal transduction pathways contribute to the induction of DARPP-32 protein levels by BDNF and that the effects are on both the transcriptional and translational levels. It also appears that PI3K is upstream of cdk5/p35, and its activation can lead to an increase in p35 protein levels. These data support the presence of multiple signal transduction pathways mediating expression of DARPP-32 in vitro, including a novel, important pathway via by which PI3K regulates the contribution of cdk5/p35.