Function of Wnts in dopaminergic neuron development.

Dopaminergic (DA) neurons in the ventral midbrain (VM) are one of the major cell types lost in Parkinson's disease (PD). Proof of principle exists for cell replacement therapies for PD, but wider application is halted by the unavailability of abundant sources of DA neurons. Stem cells might constitute one of these sources. However, efficient protocols promoting their specific differentiation into a DA neuronal phenotype are required. In this review, we summarize the latest findings concerning the contribution of the Wnt family of glycolipoproteins in the development of VM DA neurons. Regulators of Wnt signaling are involved in several neurodevelopmental processes. Recent results indicate that Wnts are key regulators of proliferation and differentiation of DA precursors during VM neurogenesis and different Wnts have specific and unique activity profiles. Interestingly, chemical inhibitors of glycogen synthase kinase-3beta stabilize beta-catenin and increase DA differentiation in VM precursor cultures. We hereby propose that Wnts are likely to contribute in the future to improve stem/precursor cell replacement therapy approaches to PD.