Differential regulation of midbrain dopaminergic neuron development by Wnt-1, Wnt-3a, and Wnt-5a.
The Wnts are a family of glycoproteins that regulate cell proliferation, fate decisions, and differentiation. In our study, we examined the contribution of Wnts to the development of ventral midbrain (VM) dopaminergic (DA) neurons. Our results show that beta-catenin is expressed in DA precursor cells and that beta-catenin signaling takes place in these cells, as assessed in TOPGAL [Tcf optimal-promoter beta-galactosidase] reporter mice. We also found that Wnt-1, -3a, and -5a expression is differentially regulated during development and that partially purified Wnts distinctively regulate VM development. Wnt-3a promoted the proliferation of precursor cells expressing the orphan nuclear receptor-related factor 1 (Nurr1) but did not increase the number of tyrosine hydroxylase-positive neurons. Instead, Wnt-1 and -5a increased the number of rat midbrain DA neurons in rat embryonic day 14.5 precursor cultures by two distinct mechanisms. Wnt-1 predominantly increased the proliferation of Nurr1+ precursors, up-regulated cyclins D1 and D3, and down-regulated p27 and p57 mRNAs. In contrast, Wnt-5a primarily increased the proportion of Nurr1+ precursors that acquired a neuronal DA phenotype and up-regulated the expression of Ptx3 and c-ret mRNA. Moreover, the soluble cysteine-rich domain of Frizzled-8 (a Wnt inhibitor) blocked endogenous Wnts and the effects of Wnt-1 and -5a on proliferation and the acquisition of a DA phenotype in precursor cultures. These findings indicate that Wnts are key regulators of proliferation and differentiation of DA precursors during VM neurogenesis and that different Wnts have specific and unique activity profiles.
Castelo-Branco
Gonçalo
G
Laboratory of Molecular Neurobiology, Medical Biochemistry, and Biophysics, Karolinska Institute, 171-77 Stockholm, Sweden.
Wagner
Joseph
J
Rodriguez
Francisco J
FJ
Kele
Julianna
J
Sousa
Kyle
K
Rawal
Nina
N
Pasolli
Hilda Amalia
HA
Fuchs
Elaine
E
Kitajewski
Jan
J
Arenas
Ernest
E
D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000502:physiology*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D008297:Male; D008636:Mesencephalon / Q000502:physiology*; D051379:Mice; D008934:Mitogens / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; D051155:Wnt1 Protein; D051154:Wnt2 Protein; D029961:Zebrafish Proteins; D051176:beta Catenin
C495267:CTNNB1 protein, mouse; C495268:Ctnnb1 protein, rat; D003598:Cytoskeletal Proteins; D008934:Mitogens; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; C085389:WNT5A protein, human; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse; C495245:Wnt1 protein, rat; D051154:Wnt2 Protein; D029961:Zebrafish Proteins; D051176:beta Catenin