AKT and CDK5/p35 mediate brain-derived neurotrophic factor induction of DARPP-32 in medium size spiny neurons in vitro.
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.
Bogush
Alexey
A
Farber Institute for Neurosciences and Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Pedrini
Steve
S
Pelta-Heller
Joshua
J
Chan
Tung
T
Yang
Qian
Q
Mao
Zixu
Z
Sluzas
Emily
E
Gieringer
Tracy
T
Ehrlich
Michelle E
ME
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D002478:Cells, Cultured; D051360:Cyclin-Dependent Kinase 5 / Q000502:physiology*; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000096:biosynthesis*; D006816:Huntington Disease / Q000188:drug therapy; D051379:Mice; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011494:Protein Kinases / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D012402:Rotenone / Q000031:analogs & derivatives / Q000494:pharmacology; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D000077191:Wortmannin
D000730:Androstadienes; D019208:Brain-Derived Neurotrophic Factor; D051360:Cyclin-Dependent Kinase 5; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D051057:Proto-Oncogene Proteins c-akt; D012402:Rotenone; D020123:Sirolimus; D058570:TOR Serine-Threonine Kinases; D000077191:Wortmannin; C497929:Ppp1r1b protein, mouse; C089495:neuronal Cdk5 activator (p25-p35); C546843:mTOR protein, mouse; C495906:Cdk5 protein, mouse; C107676:deguelin