Differences in neurogenic potential in floor plate cells along an anteroposterior location: midbrain dopaminergic neurons originate from mesencephalic floor plate cells

Abstract

Directed differentiation and purification of mesencephalic dopaminergic (mesDA) neurons from stem cells are crucial issues for realizing safe and efficient cell transplantation therapies for Parkinson's disease. Although recent studies have identified the factors that regulate mesDA neuron development, the mechanisms underlying mesDA neuron specification are not fully understood. Recently, it has been suggested that mesencephalic floor plate (FP) cells acquire neural progenitor characteristics to generate mesDA neurons. Here, we directly examined this in a fate mapping experiment using fluorescence-activated cell sorting (FACS) with an FP cell-specific surface marker, and demonstrate that mesencephalic FP cells have neurogenic activity and generate mesDA neurons in vitro. By contrast, sorted caudal FP cells have no neurogenic potential, as previously thought. Analysis of dreher mutant mice carrying a mutation in the Lmx1a locus and transgenic mice ectopically expressing Otx2 in caudal FP cells demonstrated that Otx2 determines anterior identity that confers neurogenic activity to FP cells and specifies a mesDA fate, at least in part through the induction of Lmx1a. We further show that FACS can isolate mesDA progenitors, a suitable transplantation material, from embryonic stem cell-derived neural cells. Our data provide insights into the mechanisms of specification and generation of mesDA neurons, and illustrate a useful cell replacement approach for Parkinson's disease.

Transcriptome analysis reveals transmembrane targets on transplantable midbrain dopamine progenitors

“…These results compare favorably with previous attempts to sort and graft VM progenitors by targeting of the transmembrane protein Corin (2), a marker for floor plate cells in the developing VM (34). These earlier experiments provided the important proof of principle that mDA progenitors could be identified and , and (M-P) Igsf8.…”

ES cell-derived renewable and functional midbrain dopaminergic progenitors

“…During early mouse CNS development, Otx2 is expressed in forebrain and midbrain (7), whereas Corin is expressed in floor plate (4). Based on these observations (Fig.…”

“…These extrinsic signals initiate the regulatory cascades leading to mDA development by inducing key transcription factors, including FoxA1/A2, Otx2, and Lmx1a/1b in mDA NP domains, followed later by Nurr1 and Pitx3 in mDA neuronal domains (1,2). Among these key transcription factors, FoxA2 plays an important role in inducing floor plate cells (3), which were recently shown to be mDA progenitors (4,5). Another transcription factor, Otx2, is specifically expressed in the NP domain of forebrain and midbrain and can induce the mesencephalic floor plate phenotype when ectopically expressed in the more caudal floor plate (4).…”

Spatiotemporally separable Shh domains in the midbrain define distinct dopaminergic progenitor pools

“…Recent lineage studies have revealed a surprising embryonic origin of mDA at the ventral midline of the midbrain (10,(12)(13)(14)(15). Using a Shh::Cre driver, we have definitively shown that most mDA are derived from the floor plate (FP), operationally defined by the expression of Shh (10,15).…”