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- Deng, QL, et al.
(författare)
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Specific and integrated roles of Lmx1a, Lmx1b and Phox2a in ventral midbrain development
- 2011
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 1477-9129 .- 0950-1991. ; 138:16, s. 3399-3408
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Tidskriftsartikel (refereegranskat)abstract
- The severe disorders associated with a loss or dysfunction of midbrain dopamine neurons (DNs) have intensified research aimed at deciphering developmental programs controlling midbrain development. The homeodomain proteins Lmx1a and Lmx1b are important for the specification of DNs during embryogenesis, but it is unclear to what degree they may mediate redundant or specific functions. Here, we provide evidence showing that DN progenitors in the ventral midbrain can be subdivided into molecularly distinct medial and lateral domains, and these subgroups show different sensitivity to the loss of Lmx1a and Lmx1b. Lmx1a is specifically required for converting non-neuronal floor-plate cells into neuronal DN progenitors, a process that involves the establishment of Notch signaling in ventral midline cells. On the other hand, lateral DN progenitors that do not appear to originate from the floor plate are selectively ablated in Lmx1b mutants. In addition, we also reveal an unanticipated role for Lmx1b in regulating Phox2a expression and the sequential specification of ocular motor neurons (OMNs) and red nucleus neurons (RNNs) from progenitors located lateral to DNs in the midbrain. Our data therefore establish that Lmx1b influences the differentiation of multiple neuronal subtypes in the ventral midbrain, whereas Lmx1a appears to be exclusively devoted to the differentiation of the DN lineage.
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- Holmberg, J, et al.
(författare)
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Maintaining differentiated cellular identity
- 2012
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Ingår i: Nature reviews. Genetics. - : Springer Science and Business Media LLC. - 1471-0064 .- 1471-0056. ; 13:6, s. 429-439
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Tidskriftsartikel (refereegranskat)
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- Metzakopian, E, et al.
(författare)
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Genome-wide characterization of Foxa2 targets reveals upregulation of floor plate genes and repression of ventrolateral genes in midbrain dopaminergic progenitors
- 2012
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 1477-9129 .- 0950-1991. ; 139:14, s. 2625-2634
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factors Foxa1 and Foxa2 promote the specification of midbrain dopaminergic (mDA) neurons and the floor plate. Whether their role is direct has remained unclear as they also regulate the expression of Shh, which has similar roles. We characterized the Foxa2 cis-regulatory network by chromatin immunoprecipitation followed by high-throughput sequencing of mDA progenitors. This identified 9160 high-quality Foxa2 binding sites associated with 5409 genes, providing mechanistic insights into Foxa2-mediated positive and negative regulatory events. Foxa2 regulates directly and positively key determinants of mDA neurons, including Lmx1a, Lmx1b, Msx1 and Ferd3l, while negatively inhibiting transcription factors expressed in ventrolateral midbrain such as Helt, Tle4, Otx1, Sox1 and Tal2. Furthermore, Foxa2 negatively regulates extrinsic and intrinsic components of the Shh signaling pathway, possibly by binding to the same enhancer regions of co-regulated genes as Gli1. Foxa2 also regulates the expression of floor plate factors that control axon trajectories around the midline of the embryo, thereby contributing to the axon guidance function of the floor plate. Finally, this study identified multiple Foxa2-regulated enhancers that are active in the floor plate of the midbrain or along the length of the embryo in mouse and chick. This work represents the first comprehensive characterization of Foxa2 targets in mDA progenitors and provides a framework for elaborating gene regulatory networks in a functionally important progenitor population.
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