Electric signals regulate directional migration of ventral midbrain derived dopaminergic neural progenitor cells via Wnt/GSK3β signaling Jia Liu a,b,1 , Bangfu Zhu b,1 , Gaofeng Zhang b , Jian Wang c , Weiming Tian d , Gong Ju c , Xiaoqing Wei b , Bing Song b,e, ⁎ a Laboratory Animal Center, China Medical University, Shenyang, 110001, China b School of Dentistry, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XY, UK c Institute of Neurosciences, Fourth Military Medical University, 169 West Changle Road, Xi'an 710032, China d Bio-X Center, School of Life Science and Technology, Harbin Institute of Technology, Harbin 150080, China e Department of Dermatology, China Medical University, Shenyang, 110001, China abstract article info Article history: Received 5 March 2014 Revised 16 July 2014 Accepted 16 September 2014 Available online 28 September 2014 Keywords: Ventral midbrain Neural progenitor cell Dopaminergic neurons Migration Electric fields Wnt/GSK3β signaling pathway Neural progenitor cell (NPC) replacement therapy is a promising treatment for neurodegenerative disorders in- cluding Parkinson's disease (PD). It requires a controlled directional migration and integration of NPCs, for exam- ple dopaminergic (DA) progenitor cells, into the damaged host brain tissue. There is, however, only limited understanding of how to regulate the directed migration of NPCs to the diseased or damaged brain tissues for re- pair and regeneration. The aims of this study are to explore the possibility of using a physiological level of elec- trical stimulation to regulate the directed migration of ventral midbrain NPCs (NPCs vm ), and to investigate their potential regulation via GSK3β and associated downstream effectors. We tested the effects of direct- current (DC) electric fields (EFs) on the migration behavior of the NPCs vm . A DC EF induced directional cell migra- tion toward the cathode, namely electrotaxis. Reversal of the EF polarity triggered a sharp reversal of the NPC vm electrotaxis. The electrotactic response was both time and EF voltage dependent. Pharmacologically inhibiting the canonical Wnt/GSK3β pathway significantly reduced the electrotactic response of NPCs vm , which is associ- ated with the down-regulation of GSK3β phosphorylation, β-catenin activation and CLASP2 expression. This was further proved by RNA interference of GSK3β, which also showed a significantly reduced electrotactic re- sponse in association with reduced β-catenin activation and CLASP2 expression. In comparison, RNA interference of β-catenin slightly reduced electrotactic response and CLASP2 expression. Both pharmacological inhibition of Wnt/GSK3β and RNA interference of GSK3β/β-catenin clearly reduced the asymmetric redistribution of CLASP2 and its co-localization with α-tubulin. These results suggest that Wnt/GSK3β signaling contributes to the electrotactic response of NPCs vm through the coordination of GSK3β phosphorylation, β-catenin activation, CLASP2 expression and asymmetric redistribution to the leading edge of the migrating cells. Crown Copyright © 2014 Published by Elsevier Inc. All rights reserved. Introduction Parkinson's disease (PD) is a neurodegenerative disorder with a triad of motor symptoms associated with a predominant loss of dopami- nergic (DA) neurons in the substantia nigra pars compacta (Shimada et al., 2009). Neural progenitor cell (NPC) replacement therapy has great potential to improve the clinical outcome in treating PD. It in- volves either the transplantation of NPCs/DA neurons or the promotion and recruitment of the surrounding NPCs/DA neurons. However, very few NPCs could survive if directly transplanted to the site of damage because of the adverse endogenous environment (Kelly et al., 2004). One of the potential treatments is therefore to transplant stem cells to the region adjacent to the injury site and later to induce them to migrate directionally to the damage site once the endogenous environment has improved. Unfortunately, the mechanism for regulating the directional migration of NPCs, including dopaminergic progenitor cells, to the diseased or damaged site during repair and regeneration is poorly understood. Deep brain stimulation (DBS) is an FDA-approved surgical treatment for the management of advanced PD. When PD motor complication is inadequately managed with medication, DBS, as the surgical interven- tion of choice, could significantly improve the motor symptoms and the patient's quality of life, even though the mechanism and duration of therapy is still relatively uncertain (Weaver et al., 2009; Dustin et al., 2011). There is currently no definitive evidence for whether the electric signals produced by DBS could have any influence on cellular behavior in the nearby niche. Considering the high conductivity of the brain tissue, DBS could produce electric currents which spread Experimental Neurology 263 (2015) 113–121 ⁎ Corresponding author at: School of Dentistry, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF14 4XY, UK. E-mail address: SongB3@cardiff.ac.uk (B. Song). 1 These authors contributed equally to the paper. http://dx.doi.org/10.1016/j.expneurol.2014.09.014 0014-4886/Crown Copyright © 2014 Published by Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Experimental Neurology journal homepage: www.elsevier.com/locate/yexnr