The importance of Wnt5a in DA axon morphogenesis was further verified in forward, reverse, -3 forward, reverse, forward, reverse, forward, reverse, increases the number of TH+ fibers in the medial forebrain bundle and the innervation of the striatum in vivo The contribution of Wnt5a to DA axon growth and guidance was further examined by inspecting the trajectory of TH+ axons in the mice. (F) Image illustrating the level of the MFB at which neurite counts were performed (HP, hippocampus; Ctx, cortex). (I) Image illustrating the area of the lateral striatum delineated for stereological estimates of TH+ terminal density. VM neurons. Immunocytochemistry for all those neurons (TUJ1+) revealed that (A) Fz3-CRD and (B) RYK-Fc had no effect on neurite length of non-TH+ neurons within the VM, indicating that the effects seen in Fig. 5 were specific to DA neurites. Furthermore, the absence of an effect of Fz3-CRD and RYK-Fc on the general neuronal population verifies the lack of toxicity of these proteins at the doses selected.(TIF) pone.0018373.s002.tif (102K) GUID:?2CE03D07-307F-43F5-BCD6-263B7750EDE3 Physique S3: Young mice are shorter (A’ and B’, arrow heads) and less organized/tightly fasciculated (A, B, arrows).(TIF) pone.0018373.s003.tif (3.2M) GSK1838705A GUID:?1F542BD4-6935-460F-BA50-E355B11186EB Abstract During development, precise temporal and spatial gradients are responsible for guiding axons to their appropriate targets. Within the developing ventral midbrain (VM) the cues that guide dopaminergic (DA) axons to their forebrain targets remain to be fully elucidated. Wnts are morphogens that have been identified as axon guidance molecules. Several Wnts are GSK1838705A expressed in the VM where they regulate the birth of DA neurons. Here, we describe that a precise temporo-spatial expression of Wnt5a accompanies the development of nigrostriatal APOD projections by VM DA neurons. In mice at E11.5, is expressed in the VM where it was found to promote DA neurite and axonal growth in VM primary cultures. By E14.5, when DA axons are approaching their striatal target, Wnt5a causes DA neurite retraction in primary cultures. Co-culture of VM explants with Wnt5a-overexpressing cell aggregates revealed that Wnt5a is usually capable of repelling DA neurites. Antagonism experiments revealed that the effects of Wnt5a are mediated by the Frizzled receptors and by the small GTPase, Rac1 (a component of the non-canonical Wnt planar cell polarity pathway). Moreover, the effects were specific as they could be blocked by Wnt5a antibody, sFRPs and RYK-Fc. The importance of Wnt5a in DA axon morphogenesis was further verified in forward, reverse, -3 forward, reverse, forward, reverse, forward, reverse, increases the number of TH+ fibers in the medial forebrain bundle and the innervation of the striatum in vivo The contribution of Wnt5a to DA axon growth and guidance was further examined by inspecting the trajectory of GSK1838705A TH+ axons in the mice. (F) Image illustrating the level of the MFB at which neurite counts were performed GSK1838705A (HP, hippocampus; Ctx, cortex). (I) Image illustrating the area of the lateral striatum delineated for stereological estimates of TH+ terminal density. (GCK) Confocal photomicrographs illustrating differences in the midbrain dopaminergic pathway of and that mice are shorter (A’ and B’, arrow heads) and less organized/tightly fasciculated (A, B, arrows). (TIF) Click here for additional data file.(3.2M, tif) Footnotes Competing Interests: The authors have declared that no competing interests exist. Funding: This work was supported by grants from the Australian National Health and Medical Research Council (NHMRC #566740) and the Bethlehem Griffith Research Foundation (BGRF), Australia. C.L.P. was supported by a Human Frontiers Science Program Long-Term Training Fellowship, NHMRC CJ Martin Fellowship, and NHMRC Career Development Award. B.D.B. is usually supported by an Australian Postgraduate Award. S.A.S. is usually supported by an NHMRC Senior Research Fellowship. The work of E.A. was supported by grants from the Swedish Research Council (VR2008:2811 and DBRM), Norwegian Research Council and Karolinska Institutet. The funders had no role in study design, data collection and analysis, decision to publish, GSK1838705A or preparation of the manuscript..