Initiation of dopaminergic differentiation of Nurr1(-) mesencephalic precursor cells depends on activation of multiple mitogen-activated protein kinase pathways.
Interleukin-1 (IL-1) plays a pivotal role in terminal dopaminergic differentiation of midbrain-derived neural precursor cells already committed to the mesencephalic dopaminergic phenotype (named mdNPCs for mesencephalic dopaminergic neural precursor cells). Here we characterized the molecular events in long-term expanded rat nuclear receptor related-1(-) (Nurr1(-)) mdNPCs in response to IL-1beta during their terminal dopaminergic specification. We showed that IL-1beta induced a rapid induction of mRNA of dopaminergic key fate-determining transcription factors, such as Nurr1 and Pitx3, and a subsequent increase of tyrosine hydroxylase protein as an early marker for dopaminergic neurons in vitro. These effects of IL-1beta were specific for mdNPCs and were not observed in striatal neural precursor cells (NPCs). Surprisingly, IL-1beta did not activate the NF-kappaB pathway or the transcription factor activating protein 1 (AP-1), but inhibition of nuclear translocation of NF-kappaB by SN50 facilitated IL-1beta-induced Nurr1 expression and dopaminergic differentiation of mdNPCs. Incubation of mdNPCs with IL-1beta led to a rapid phosphorylation of ERK1/2 and p38 mitogen-activated protein (MAP) kinases within 1 to 3 hours, whereas Jun kinase was not phosphorylated in response to IL-1beta. Consistently, inhibition of the ERK1/2 pathway or p38 MAP kinase blocked Nurr1 upregulation and further dopaminergic specification of mdNPCs, but not differentiation into MAP2ab(+) neurons. IL-1 receptor antagonist did not block early dopaminergic differentiation events, suggesting that the effects of IL-1beta are not mediated through activation of IL-1 receptor type I. Our results indicate that induction of terminal dopaminergic specification of Nurr1(-) mdNPCs by IL-1beta depends on activation of the ERK1/2 and p38 MAP kinase pathway.
Sabolek
Michael
M
Department of Neurology, University of Ulm, Ulm, Germany.
Baumann
Bernd
B
Heinrich
Maria
M
Meyer
Anne K
AK
Herborg
Anna
A
Liebau
Stefan
S
Maisel
Martina
M
Hermann
Andreas
A
Ventz
Katharina
K
Schwarz
Johannes
J
Wirth
Thomas
T
Storch
Alexander
A
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D053583:Interleukin-1beta / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008636:Mesencephalon / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2 / Q000172:deficiency / Q000378:metabolism; D010641:Phenotype; D051381:Rats; D053573:Receptors, Interleukin-1 Type I / Q000096:biosynthesis
D004268:DNA-Binding Proteins; D053583:Interleukin-1beta; D016328:NF-kappa B; C539884:Nr4a2 protein, rat; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D053573:Receptors, Interleukin-1 Type I; D020928:Mitogen-Activated Protein Kinases